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  1. #1

    Default A synthetic route to damascenone family compounds (advanced chemistry)

    To start off with, a warning, this thread isn't for most of you Basenotes readers, it deals with some moderately advanced organic chemistry, so if that's not your thing, best to leave now.

    I know there's at least a few of you (maybe only 3 or 4) who are interested in the organic chemistry of new fragrance compounds, or even experiment making a few on your own.

    Damascenones are a family of typically rose-like smelling compounds, and they smell even more beautiful than the closely chemically related family of Ionones.
    Ionones (violet and powdery) are very common in perfumery and are easy enough to make. Unfortunately damascenones have been much more chemically challenging to make, and currently it's actually cheaper to isolate damascenone from natural damask rose extract than it is to make it synthetically. This makes it much more expensive.
    This is a real stumbling block because damascenone is nearly essential for imbuing genuine and beautiful smelling rose notes to a fragrance. Damascenone is the best component in the smell of roses.

    If you look at the structural difference between ionones and damascenone, you see that in ionones the oxygen atom (ketone group) is towards the end of the chain, away from the ring. For damascenone, the ketone group is immediately adjacent to the ring, right next to it. In terms of olfactory structure, I believe it's those methyl groups right next to it that shield the ketone oxygen atom and leads to the unique rose smell. Of course this makes synthesis much more problematic because if you start out with the basic building blocks it's impractical to selectively oxidize that first carbon atom on the chain next to the ring. Ionones are much easier because they're made by condensing acetone onto citral (Aldol reaction) and then catalyzing the resulting product into a ring.

    Well, I am going to propose a different synthetic route to damascenones, one that's far easier than other conventional ones. An Aldol condensation can be used, but this time sort of a reverse way from how Ionones are typically made. Have the ketone (more accurately aceto- ) group on the side of the ring to begin with. Then condense an aldehyde chain (acetaldehyde, green apple smell) onto that. Aldol condensations are pretty easy to do, can be done in aqueous medium with some concentrated hydrochloric acid.

    Now you might be wondering about the other side, how do we make that ring with the attached ketone group? Well, I'm not going to go into that detail here but it's not too difficult to do. Think about Iso E Super, Cedryl Ketone, Fixamber. All pretty standard in perfumery now, not too impractical to synthesize.

    Even if not that, acetaldehyde could always be condensed on to nitro group on the ring, leaving the alcohol, reduce the nitro to an amine, go the diazonium route to remove the amine group, and then eventually get around to oxidizing the alcohol to a ketone. (or maybe temporarily turn that alcohol into a bromine to protect it from oxidation, or something like that, CuI catalyst can hydrolyze it back afterwards)
    Or I could also cite the first ingenious catalytic step in Sungwoo Hong and E. J. Corey's synthesis of Arborone.

    (A current lab synthetic route for damascenone involves organo-lithium reduction on a carboxylic ester, reducing the carboxylate to a ketone simultaneously while the ester is swapped out with the organo- building block that was on the lithium. This of course is expensive, and makes it not so practical to try to commercially scale up.)

    I believe this route could maybe open the door to a whole new family of damascenone compounds. And they would not be too expensive.

    These would of course be analogous to Ionones, but of course with a more beautiful exquisite true rose odor, rather than powdery violets.


    Well, I don't know if any of you found this interesting, or were even able to understand half of what I was talking about here. I just had to share my rough idea here. (half-baked, I know) I know this isn't exactly a fragrance chemistry forum but maybe one or two of you will appreciate this.
    Maybe there's even a perfume researcher in the industry reading this who will take this idea.

  2. #2

    Default Re: A synthetic route to damascenone family compounds (advanced chemistry)

    Quote Originally Posted by parker25mv View Post
    Damascenones are a family of typically rose-like smelling compounds, and they smell even more beautiful than the closely chemically related family of Ionones.
    I disagree with that statement! You know how the saying goes: You shouldn't compare orris with roses

    Quote Originally Posted by parker25mv View Post
    Well, I am going to propose a different synthetic route to damascenones, one that's far easier than other conventional ones.
    before having really tried it you simply can't know if it's "far easier" .... perhaps it might not work at all. Apparently you didn't look into possible side reactions which sometimes can ruin a whole idea without mercy


    Quote Originally Posted by parker25mv View Post
    Now you might be wondering about the other side, how do we make that ring with the attached ketone group? Well, I'm not going to go into that detail here but it's not too difficult to do. Think about Iso E Super, Cedryl Ketone, Fixamber. All pretty standard in perfumery now, not too impractical to synthesize.
    but this is most essential! You really have to get "into detail" here
    You can't list different ketones and generalize that any ketone is therefore simple to make

  3. #3

    Default Re: A synthetic route to damascenone family compounds (advanced chemistry)

    Quote Originally Posted by parker25mv View Post
    currently it's actually cheaper to isolate damascenone from natural damask rose extract than it is to make it synthetically.
    where did you hear that ??? just look at the prices and calculate

    Quote Originally Posted by parker25mv View Post
    Even if not that, acetaldehyde could always be condensed on to nitro group on the ring, leaving the alcohol, reduce the nitro to an amine, go the diazonium route to remove the amine group, and then eventually get around to oxidizing the alcohol to a ketone. (or maybe temporarily turn that alcohol into a bromine to protect it from oxidation, or something like that, CuI catalyst can hydrolyze it back afterwards)
    Or I could also cite the first ingenious catalytic step in Sungwoo Hong and E. J. Corey's synthesis of Arborone.
    condense what onto a nitro group ?
    the reactions you mentioned are typically performed on aromatic rings.
    by the first step in Coreys synth you mean the enantioselective Diels Alder reaction ? have a look where the double bond would end up, possible isomers etc
    The carbonyl group in ionones can be shifted to make damascones, a reaction described by Ohloff and Schulte-Elte in the 70s

  4. #4

    Default Re: A synthetic route to damascenone family compounds (advanced chemistry)

    by the way, please take my comments as constructive criticism where you need to improve the idea, not as discouragement to think about fragrance chemistry

  5. #5

    Default Re: A synthetic route to damascenone family compounds (advanced chemistry)

    Quote Originally Posted by 'Timon View Post
    The carbonyl group in ionones can be shifted to make damascones, a reaction described by Ohloff and Schulte-Elte in the 70s
    Finally, someone who knows more about this than me!

    I did find a patent ( CN104003860 ) that refers to conversion of an ionone to damascenone by converting the ketone to an oxime, oxidizing to form a transient ring (critical that there not be any water in there, I would think, for proper formation of the ring) with the oxygen now on the proper site, reducing this with metallic sodium, the intermediate (not shown in the patent) oxidized again by a halogen, and finally that halogen (on the site of the former oxygen) eliminated with a base, leaving the unsaturated double bond.

    I'm sorry, I couldn't find Ohloff and Schulte-Elte 's synthesis. Do you mind very briefly going over what it was?
    (Is it similar to the above?)

  6. #6

    Default Re: A synthetic route to damascenone family compounds (advanced chemistry)

    Quote Originally Posted by 'Timon View Post
    I disagree with that statement! You know how the saying goes: You shouldn't compare orris with roses
    You are right, I came close to adding "In my opinion". Anyway, I think we can both agree that damascenone is one of the most "perfume-like" compounds, and that it's scarcer and very much more expensive than Ionones. Any perfume house can add as much Ionones as they want and not worry about cost, but when it comes to damascenone they will often get much more stingy. I think if damascenone was cheaper this would be a fragrance note used far more often.

    I certainly think damascenone has more utility in perfumes than ionone, even though the fragrance smell is less neutral. Ionones are often there more for an "effect" (brightness, powdery, ethereal), damascenone is used to add an exquisite true rose note.

    Givaudan has come out with a new molecule designed as a less expensive damascenone replacement, Pomarose, but right now it's still a captive.

    As far as the smell of orris, I was about to get out some orivone, it's cheap enough.

  7. #7

    Default Re: A synthetic route to damascenone family compounds (advanced chemistry)

    You should consider being less condescending if you want the best results from discussion. You are in a perfumery forum, and as it is chemistry is a shadow compared to the light that is the art of making perfumery, yet you don't see the artists here talking down on you, do ya?

    Why have you not tried this experiment yourself yet?

  8. #8

    Default Re: A synthetic route to damascenone family compounds (advanced chemistry)

    Quote Originally Posted by CutSmut View Post
    You should consider being less condescending if you want the best results from discussion.
    Sorry if I come across as condescending, I don't mean to be. I've been told that before.

    Just for constructive criticism and my benefit, could you maybe tell me what types of things I could do to communicate differently?

    I really did not mean to be sarcastic when I said "Finally, someone who knows more about this than me!"
    I was just happily surprised to find someone with your knowledge here who is able to comment on this thread.

  9. #9

    Default Re: A synthetic route to damascenone family compounds (advanced chemistry)

    Quote Originally Posted by parker25mv View Post
    (Is it similar to the above?)
    yes it's almost identical! I looked it up again and actually the reaction was originally reported by Büchi. However Ohloff and colleagues at Firmenich applied this elegant method to other Ionones in the same year, to yield for example gamma Damascone.
    I need to look at the Chinese patent to see where it really differs and in how far it presents any advantage

  10. #10

    Default Re: A synthetic route to damascenone family compounds (advanced chemistry)

    Quote Originally Posted by parker25mv View Post
    I certainly think damascenone has more utility in perfumes than ionone, even though the fragrance smell is less neutral.

    Givaudan has come out with a new molecule designed as a less expensive damascenone replacement, Pomarose, but right now it's still a captive.

    As far as the smell of orris, I was about to get out some orivone, it's cheap enough.

    again I think this is an apple pear situation and there is no special point in comparing just these two families, since they are quite different despite the structural similarity at first sight.
    for fine fragrance the cost of Damascones is less problematic than the allergy restrictions. If these molecules wouldn't be so important for perfumery, you can be absolutely sure that IFRA would have completely prohibited them already.
    now Orivone is completely different altogether

    btw, how do you want to know that Pomarose is less expensive ?

  11. #11

    Default Re: A synthetic route to damascenone family compounds (advanced chemistry)

    Quote Originally Posted by parker25mv View Post
    Sorry if I come across as condescending, I don't mean to be. I've been told that before.

    Just for constructive criticism and my benefit, could you maybe tell me what types of things I could do to communicate differently?

    I really did not mean to be sarcastic when I said "Finally, someone who knows more about this than me!"
    I was just happily surprised to find someone with your knowledge here who is able to comment on this thread.
    Allow me to communicate to you that I lack the knowledge of organic chemistry, rather than taking the assumption that I do, and then making crude comments such as "Well I don't know if even half of you are able to understand what I'm talking about". Sometimes people who know little about a problem are the most suited to providing a new perspective that leads to solving the problem; and other times it's useless trite that can be ignored. You can't procure that information from others though if you immediately turn people antagonistic towards you with your language. Just my thoughts, and no apology is necessary if anything I should be apologizing to you and taking my own advice as I was quite hostile in my own comment.

    I didn't take your statement about finally someone who knows more than me to be sarcastic at all. It is a wonderful moment when we have this specialized knowledge and we find one in the crowds who can teach us something.

    Alll that being said I'll leave this thread now as I do not wish to change to course of conversation away from your idea. Good luck finding your solution my friend.

  12. #12

    Default Re: A synthetic route to damascenone family compounds (advanced chemistry)

    Parker- do you think natural enzyme methods as described by Tisserand and others would be easier/ cheaper?
    Between attempts at that, and some info about the way tobacco is fermented, I am 99% sure I made this from just the starfruit. I think unfortunately there is only a 2 week window in November these skins will do that. I tried to replicate this experiment all winter with no luck. I would like to send you some of this enzyme in a coupIe of months if you are willing test it on different things containing carotenes.
    Also I didn't know there is a whole 'damascenone family', thought it was just one thing. Tried the enzyme solution on several orange-red things, hibiscus reaction being the most pleasant, and paprika producing the strongest.
    Thanks for the additional info, you are right, don't understand most of it but I like to read your ideas on this and Nootkatone. No idea why on the nootkatone since I will probably never get the synthetic version.

  13. #13

    Default Re: A synthetic route to damascenone family compounds (advanced chemistry)

    Quote Originally Posted by Thea in Fl View Post
    Parker- do you think natural enzyme methods as described by Tisserand and others would be easier/ cheaper?
    That's a really difficult one to say. I'm not really in the position to know.

    Of course it all depends.
    I believe that in some cases the most economical route is the one that's put into commercialization first, when economics of scale brings down the cost way down, and the real experience and industry investment has already been made verifying it can be a commercially viable process. Sometimes it's just not practical for them to reinvent the wheel, even if they have some theoretical basis to believe there's another way that could be better. That's just how business goes.

    I've been disappointed in the past that Evolva's fermentation-derived nootkatone and santalol process never seemed to get off the ground.


    Quote Originally Posted by Thea in Fl View Post
    Also I didn't know there is a whole 'damascenone family', thought it was just one thing.
    There's not. Right now there's not a 'damascenone family' because they are difficult to make synthetically. I was just pointing out that in the future a better synthetic route could open the way to a damascenone family and new damascenone-like componds, in the same way that perfumers now have a palette of different ionones to work with.

    If there are different stereoisomers or analogues of damascenone, they've most likely been made on-site in the lab by fragrance researchers, not anywhere near being available for perfumists. Nothing for you to worry about, I doubt they've discovered anything at this point that's more interesting than the natural.

    (Also I don't want to make it sound like I know what I'm talking about here because I really don't)

    Quote Originally Posted by Thea in Fl View Post
    Thanks for the additional info, you are right, don't understand most of it but I like to read your ideas on this and Nootkatone.
    Also for any of you advanced chemistry people who may be interested, I worked out a really half-baked rough outline of an idea for a route to synthetic nootkatone in post #7 of this thread: Where to buy nootkatone (not from grapefruit) ?

  14. #14

    Default Re: A synthetic route to damascenone family compounds (advanced chemistry)

    I think because the juice industry has so many tons of rind waste to dispose of, getting use for oils and other product is cheaper there.

  15. #15

    Default Re: A synthetic route to damascenone family compounds (advanced chemistry)

    Quote Originally Posted by Thea in Fl View Post
    I think because the juice industry has so many tons of rind waste to dispose of, getting use for oils and other product is cheaper there.
    For valencene, yes, that may be the case, but not for nootkatone.
    Evolva's process involved taking that valencene and enzymatically oxidizing it to nootkatone.

    But I don't want to get too far off-topic here.

    Further off-topic, I could never understand why they never commercially isolated nootkatone from Port Orford Yellow Cedar (Nootka cypress, where the molecule Nootkatone actually got its name). The wood is very high in the stuff. Maybe it's considered an endangered species now and there's not a big enough commercial supply of the wood. Most of it is probably located in the protected Tongass National Forest and protected national parks of British Columbia. They have Sanalwood tree plantations in India and Australia, I don't see why they couldn't set up Yellow Cedar plantations in British Columbia.

    off-topic over now

  16. #16

    Default Re: A synthetic route to damascenone family compounds (advanced chemistry)

    Yes, sorry about getting off topic. I am interested in your idea, and further responses. Why is damascenone so expensive for perfume, as I read that the wine and beer industry add regularly - I wonder how this is, given the difference in prices.

  17. #17

    Default Re: A synthetic route to damascenone family compounds (advanced chemistry)

    Quote Originally Posted by Thea in Fl View Post
    Why is damascenone so expensive for perfume, as I read that the wine and beer industry add regularly - I wonder how this is, given the difference in prices.
    It takes far less of it to add subtle flavor than it does to make a perfume fragrance that will project its smell.

    You can also smell beta-damascenone if you peel off the fresh rose red skins of lychee fruit and smell them in a pile, the inner side of the shells. But you have to put your nose pretty close to it.

  18. #18

    Default Re: A synthetic route to damascenone family compounds (advanced chemistry)

    Quote Originally Posted by parker25mv View Post
    Further off-topic, I could never understand why they never commercially isolated nootkatone from Port Orford Yellow Cedar (Nootka cypress, where the molecule Nootkatone actually got its name). The wood is very high in the stuff. Maybe it's considered an endangered species now and there's not a big enough commercial supply of the wood. Most of it is probably located in the protected Tongass National Forest and protected national parks of British Columbia. They have Sanalwood tree plantations in India and Australia, I don't see why they couldn't set up Yellow Cedar plantations in British Columbia.

    off-topic over now
    So not over, you added new stuff... I think they do isolate from that tree, Sigma-Aldrich states it is natural. And because of all this sesquiterpene stuff I now know that Eremophilene is a certain class of sesquiterpenes, that's why they look the same, all these, same class. Something to do with 15 carbons that don't exactly follow the 'isoprene rule', established in 1887 or so, way over my head, but I am interested in sourcing it from the oil because I need a fungicide for a lot of outdoor shelving and possibly soil and this looks promising if I can assure the odor won't negatively affect other trees.

  19. #19

    Default Re: A synthetic route to damascenone family compounds (advanced chemistry)

    Quote Originally Posted by parker25mv View Post
    It takes far less of it to add subtle flavor than it does to make a perfume fragrance that will project its smell.

    You can also smell beta-damascenone if you peel off the fresh rose red skins of lychee fruit and smell them in a pile, the inner side of the shells. But you have to put your nose pretty close to it.
    Something wrong with my tree it had lots of fruit but the skins wouldn't turn red. Those things are gross, look just like beetle larvae inside.

  20. #20

    Default Re: A synthetic route to damascenone family compounds (advanced chemistry)

    Okay, one more time OT, I didn't want to bring up the old nootkatone thread for fear anyone will be sick of hearing about, so will put here.
    but I am thinking there are (stereoisomers?) that have different profile depending on the tree species, really just learned of that kind of thing, not very versed on chemistry... but will gain something eventually.
    What do you think, if both valencene and nootkatone are in the eremophilones class, about the possibility that the nootkatone in the cedar, and the possibly unnamed one in buddhawood has an entirely different profile than the citrus (isomer?)
    Something is really bothering me that these 'rare' molecules exist in such entirely different trees, and not at all in others, not even a cypress cedar cross (Leyland cypress) !

  21. #21

    Default Re: A synthetic route to damascenone family compounds (advanced chemistry)

    Quote Originally Posted by Thea in Fl View Post
    but I am thinking there are (stereoisomers?) that have different profile depending on the tree species,
    Well I don't know about stereoisomers, but there are three different isomers, nootkatone (grapefruit peel), eremophilone (Buddha wood, false sandalwood), and vetivone (one of the smells in vetiver), that exist in nature.
    In addition, the molecular structure of the primary chromone in oud also bears a striking resemblance to this family (except one of the atoms in the ring is replaced by oxygen, which makes the smell sweeter and smell more like band-aids, and the molecule is also attached to a long santal group which is nearly identical in structure to the santalol of sandalwood.

  22. #22

    Default Re: A synthetic route to damascenone family compounds (advanced chemistry)

    Quote Originally Posted by parker25mv View Post
    Well I don't know about stereoisomers, but there are three different isomers, nootkatone (grapefruit peel), eremophilone (Buddha wood, false sandalwood), and vetivone (one of the smells in vetiver), that exist in nature.
    In addition, the molecular structure of the primary chromone in oud also bears a striking resemblance to this family (except one of the atoms in the ring is replaced by oxygen, which makes the smell sweeter and smell more like band-aids, and the molecule is also attached to a long santal group which is nearly identical in structure to the santalol of sandalwood.
    Hmm.... the oud would make sense for fungal defense type chemicals in common, namely dreaded heart-rot fungus like armillaria, I was thinking more like salt defense mechanism.

    Thanks Parker.

    Any chance of similar in angelica root or valerian you know of?

  23. #23

    Default Re: A synthetic route to damascenone family compounds (advanced chemistry)

    Quote Originally Posted by 'Timon View Post
    but this is most essential! You really have to get "into detail" here
    You can't list different ketones and generalize that any ketone is therefore simple to make
    You asked about more specific starting materials, methyl cyclocitrone or cyclocitral may be appropriate starting materials.
    Or safranal.
    Last edited by parker25mv; 3rd October 2019 at 02:55 AM.

  24. #24

    Default Re: A synthetic route to damascenone family compounds (advanced chemistry)

    Could you provide asynthesis / reaction scheme or mechanisms for your route, please. Synthesis in words are so tedious. Thanks!

  25. #25

    Default Re: A synthetic route to damascenone family compounds (advanced chemistry)

    Quote Originally Posted by Thea in Fl View Post
    I am thinking there are (stereoisomers?) that have different profile depending on the tree species, really just learned of that kind of thing, not very versed on chemistry...
    One more to add, there is also Dihydrokaranone found in high concentration in Kyllinga odorata (Fragrant Spikesedge).
    Arcadi boix Camp had this to say about it: "One of the best chemicals I have smelled in my life, being powerfully woody, resinous, timbered extraordinarily diffusive and not easy to forget once known and smelled. This is on of the best woody chemicals in the world!"

    One study found the essential oil of Kyllinga odorata contained 53 percent Dihydrokaranone, as well as 11 percent Aristolochene (seems to be a Valencene isomer).
    Journal of Essential Oil Research, Volume 18, 2006, issue 4, p 381




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