:Talk:Isocomene

I have removed the following text from the "Biosynthesis" section of the article because it has multiple problems, including: 1) the text describes laboratory syntheses, not biosynthesis; 2) the text seems to confuse aspects of different syntheses as if they were one, for example by using references to one published synthesis to support the description of a different synthesis; 3) the text makes reference to things that are missing from the images ("reagents b through e", etc.); 4) the images contain chemistry errors; 5) the text contains factual errors and statements that just don't make sense("catalyze with heat", etc.); 6) the text is so poorly written and includes enough grammar errors to make it confusing and incomprehensible in places. Once these problems are corrected, the content can be added back into the article. -- Ed (Edgar181) 12:27, 24 October 2017 (UTC)

{{quote|File:Isocomene from enol ether copy.gifThe Weiss and Cook synthesis pathways consists of 5 steps starting with the condensation of 2 moles of dimethyl-1,3-acetonedicarboxylate and a α-dicarbonyl compound.{{Cite journal|last=Dauben|first=William G.|last2=Walker|first2=Daniel M.|date=1980|title=Formal Total Synthesis of (f)-Isocomene|url=http://pubs.acs.org/doi/abs/10.1021/jo00319a013|journal=Journal of Organic Chemistry|volume=46|issue=6|pages=1103–1108|via=ACS Publication|doi=10.1021/jo00319a013}} This reaction is catalyzed by aqueous methanol and afford a high yield of 80%. The product of this is then undergo decarboxylation in step II to remove the carboxylate functional group and allow the formation of a  cis-bicyclo[3.3.0]octa-3,7-dione. Step II is a multiple synthesis step where the compound from previous step is hydrolyze and decarboxylate through the treatment of series of reagent going from reagents b through e. The resulting product is a diketal and then is hydrolyzed into a monoketal that allow the reaction to go on to the next step. The monoketal undergo Wolff-Kishner reaction with hydrazine in aqueous potassium hydroxide in step III. Wolff-Kishner reaction turn a ketone to aalkane, the carbon oxygen double bond is broken and 2 hydrogen atoms are added to give the compound after step III. Step IV is a cyclization under the catalyst of p-toluenesulfonic acid. The reaction gives a moderate high yield of 88%. The product of this step is a β-diketone system which is then “completely nonenolized” when treated with LDA, THF and Methyl iodide. Alternative reagent for this step is sodium tert-amylate, DME and Methyl iodide.
The first ever developed synthesis path was by M.C Pirrung with enol ether as the beginning material. This synthetic method is said to be the most efficient method and afford the high yield of the desired product and also includes 5 steps. The starting reagent was let react to form a conjugated compound through Stork and Danheiser in step I. In step II, this compound then under go Grignard reaction with 5-bromo-2-methyl-1pentene, an organomagnesium compound that is also known as Grignard reagent. The reaction is catalyzed by aqueous acid and give a very high yield. The compound form is a dienone compound. It is then treat with light with the wavelength of 350 nm to allow the formation of a cycloadduct compound. The product is in a waxy solid form with a melting point ranges from 63 to 68 degree Celsius. The compound then undergo Wittig reaction: methylenetriphenylphosphorane in step IV with Witting reagent to form a new carbon carbon bond from the previously exist carbon oxygen double bond. The reaction produce the hydrocarbon that exist with several different stereochemistry. The yield of this step is also moderate with 77%. The final step is to treat the compound with TsOH - p-toluenesulfonic acid, benzene and catalyze with heat. The product formed is a racemic mixture of isocomene with an extremely high yield of 98%. The final product is collected in solid form and has a melting point of around 60 degree Celsius. This synthesis method is the most effective of all with a high overall percentage yield that is higher than 40%. {{Cite journal|last=Pirrung|first=Michael C.|date=1980|title=Total Synthesis of (f)-Isocomene and Related Studies|url=http://pubs.acs.org/doi/abs/10.1021/ja00391a016|journal=Journal of the American Chemical Society|volume=103|pages=82–87|via=ACS Publication|doi=10.1021/ja00391a016}} Another alternative way of synthesizing isocomene is through the use of rearrangement. The synthesis focused on the rearrangement ability of sesquiterpene compound through intramolecular ketene cycloadditions. This type of synthesis aim to the formation of cyclobutanone, an intermediate that can be used as a material for isocomene synthesis.{{Cite journal|last=Snider|first=Barry|last2=Beal|first2=Richard B.|date=1988|title=Total Synthesis of Sesquiterpenes via Intramolecular Ketene Cycloadditions: Isocomeneanda-cis-anda-trans-Bergamotenes, an Approach to Seychellene|url=http://pubs.acs.org/doi/abs/10.1021/jo00254a017|journal=Journal of Organic Chemistry|volume=53|issue=19|pages=4508–4515|via=ACS Publication|doi=10.1021/jo00254a017}} 

File:Isocomene WEiss and COok GIF.gif}}