Toxicity of Pumiliotoxin 251D and Synthetic Analogs to the Cotton Pest Heliothis virescens
摘要:
A series of 13 simplified analogs of frog skin derived pumiliotoxin indolizidine alkaloids was prepared and evaluated for their toxicity to the larvae of the important cotton pest Heliothis virescens. The alkyl side chain of pumiliotoxin 251D was replaced with a variety of substituents designed to influence or restrict-its conformation and its ability to act as a site of metabolic detoxification. Significantly, a substituent in the R configuration at the C-2' carbon of the side chain was required for toxicity. Computational studies suggested that this substituent may control the active conformation of the side chain. No structural modification led to a significant improvement in toxicity over the natural product.
Coupling reaction of 4-cyclopentene-1,3-diol monoacetate and lithium alkenylborates and its application to chiral synthesis of prostaglandin intermediates
作者:Shahid B. Usmani、Eisuke Takahisa、Yuichi Kobayashi
DOI:10.1016/s0040-4039(97)10655-4
日期:1998.2
3-isomers in good yields. Moreover, an unexpectedly high level of regio-selectivity is observed with the alkenylborates possessing the prostaglandin (PG) ω-chain structure. The present reaction is successfully applied to the asymmetricsynthesis of PG intermediates 9, 15, 16.
A new reaction of 1-bromoalk-1-ynes; synthesis of 3-alkylalk-1-ynes from terminal acetylenes
作者:Augustus J. Quillinan、Ejaz A. Khan、Feodor Scheinmann
DOI:10.1039/c39740001030
日期:——
The reaction of 1-bromoalk-1-ynes with two equivalents of butyl-lithium in hexane gives 3-butylalk-1-ynes; the reactive intermediate is a dilithioalkyne which can also be directly prepared fromterminalacetylenes, and selective reaction with alkyl halides in hexane occurs at the propargylic site to provide a general synthesis of 3-alkylalk-1-ynes.
Copper-Catalyzed 1,2-Addition of α-Carbonyl Iodides to Alkynes
作者:Tao Xu、Xile Hu
DOI:10.1002/anie.201410279
日期:2015.1.19
Abstractβ,γ‐Unsaturated ketones are an important class of organic molecules. Herein, copper catalysis has been developed for the synthesis of β‐γ‐unsaturated ketones through 1,2‐addition of α‐carbonyl iodides to alkynes. The reactions exhibit wide substrate scope and high functional group tolerance. The reaction products are versatile synthetic intermediates to complex small molecules. The method was applied for the formal synthesis of (±)‐trichostatin A, a histone deacetylase inhibitor.