Improved Synthesis and Deployment of (2S,3R)-2-(2Z,5Z-Octadienyl)-3-nonyloxirane, a Pheromone of the Pink Moth, Lymantria mathura
摘要:
We report two new syntheses of (2S,3R)-2-(2Z5Z-octadienyl)-3-nonyloxirane, the main sex pheromone component of the pink moth, Lymantria mathura. The key step in the first route was the construction of (Z,Z)-1-bromo-1,4-heptadiene (6), which was coupled in the final step with 2-iodomethyl-3-nonyloxirane 4 via a Grignard reaction. The second approach employed alkylation of 1,4-heptadiynyllithium with epoxy triflates 7 in ether/hexane and provided the pheromone in greater than or equal to37% overall yield from alcohol 2. The 4:1 ratio of pheromone enantiomers, reportedly the most attractive to pink moth males, can be directly crafted from appropriately selected Sharpless asymmetric epoxidation conditions.
A concise synthesis of the sexpheromones of elm spanworm as well as painted apple moth has been achieved. The key steps were the alkylation of acetylide ion, Sharpless asymmetric epoxidation and Brown’s P2-Ni reduction. This approach provided the sexpheromone of the elm spanworm (1) in 31% total yield and those of the painted apple moth (2, 3) in 26% and 32% total yields. The ee values of three final
Fleming−Tamao Oxidation and Masked Hydroxyl Functionality: Total Synthesis of (+)-Pramanicin and Structural Elucidation of the Antifungal Natural Product (−)-Pramanicin
作者:Anthony G. M. Barrett、John Head、Marie L. Smith、Nicholas S. Stock、A. J. P. White、D. J. Williams
DOI:10.1021/jo9905672
日期:1999.8.1
The total synthesis of (+)-pramanicin (41b) is reported, thereby establishing the relative and absolute stereochemistry of the naturally occurring antifungal agent. The key steps involve (i) conjugate addition of the diethyl((diethylamino)diphenylsilyl)zincate to a suitably protected gamma-lactam 3 and quenching of the resultant enolate with the alpha,beta-unsaturated gamma,delta-epoxy aldehyde 2 (X = H), (ii) Ni(acac)(2)-catalyzed hydroxylation of a beta-dicarbonyl array, and (iii) Fleming-Tamao oxidation to reveal the masked C-3 hydroxyl group.
ROUSH, WILLIAM R.;ANDO, KAORI;POWERS, DANIEL B.;PALKOWITZ, ALAN D.;HALTER+, J. AMER. CHEM. SOC., 112,(1990) N7, C. 6339-6348
作者:ROUSH, WILLIAM R.、ANDO, KAORI、POWERS, DANIEL B.、PALKOWITZ, ALAN D.、HALTER+