Enantioselective Total Synthesis of (−)-Laurenditerpenol

Abstract

A highly convergent total synthesis of (-)-laurenditerpenol has been accomplished through an organolithium to aldehyde nucleophilic addition. Preparation of the prerequisite key intermediates in optically pure form was based on an improved, short, and efficient synthesis of "wine lactone" from (S)-limonene and Corey's catalytic enantioselective Diels-Alder reaction of 2,5-dimethyl furan with diethyl fumarate.

Unusual Structure-Energy Correlations in Intramolecular Diels–Alder Reaction Transition States

“…The Diels–Alder reaction of furan has been widely used in the synthesis of complex targets and as a probe for the investigation of substituent effects [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18]. We recently reported a comprehensive, computational and experimental study of halogenation effects in intramolecular Diels–Alder reactions [19].…”

Hydrolysis of esters and dialkyl malonates mediated by t-BuNH2/LiBr/alcohol/H2O

“…With these results in hand it is evident that once the half esters of 15 and 16 are formed, their decarboxylation takes place as the negative charge at the alfa position of the respective esters could be stabilized by the aromatic ring, unlike half esters 18, 20, 22 and cyanoacetic acid 24. The selectivity in the monohydrolysis of malonate diesters using the methodology developed in this work was evidenced when longer-chain diesteres such as dimethyl succinate and dimethyl glutarate were used since the hydrolysis of these compounds afforded not the corresponding half esters (Niwayama, 2010;Niwayama, 2000;Niwayama, 2007;Rajsfus, 2013;Pitsinos, 2012) but the diacids in high yields.…”

First Stereo Selective Total Synthesis of Antimicrobial Trichoderic acid

“…Our primary focus relied upon the synthesis of the aldehyde 5 which was initiated from the commercially available 3‐methyl‐2‐cyclohexenone 9 (Scheme ). Accordingly, we have started with alkylation of ketone 9 with ethylbromoacetate 10 using LDA afforded ester enone 11 in 75 % yield, which was then subjected to a diastereoselective reduction using ( R )‐2‐Methyl‐CBS‐oxazaborolidine to afford allylic alcohol 8 in 78 % yield . The corresponding ester 8 was treated with LiOH in THF and subsequent acidic work up (pH=2) resulted in tandem sequence of saponification followed by lactonization yielded two lactones 12, 13 (2:1) as a separable mixture.…”

“…Accordingly, we have started with alkylation of ketone 9 with ethylbromoacetate 10 using LDA afforded ester enone 11 in 75 % yield, which was then subjected to a diastereoselective reduction using (R)-2-Methyl-CBS-oxazaborolidine to afford allylic alcohol 8 in 78 % yield. [6] The corresponding ester 8 was treated with LiOH in THF and subsequent acidic work up (pH = 2) resulted in tandem se- [a] Dr.…”

“…Accordingly, we have started with alkylation of ketone 9 with ethylbromoacetate 10 using LDA afforded ester enone 11 in 75 % yield, which was then subjected to a diastereoselective reduction using (R)-2-Methyl-CBS-oxazaborolidine to afford allylic alcohol 8 in 78 % yield. [6] The corresponding ester 8 was treated with LiOH in THF and subsequent acidic work up (pH = 2) resulted in tandem se- Communications DOI: 10.1002/slct.201601163 quence of saponification followed by lactonization yielded two lactones 12, 13 (2:1) as a separable mixture. Methylation of major lactone 12 was carried out using LDA and MeI at À78 o C resulted wine lactone 7 in 82 % with required stereochemistry at C7 position.…”