Isolation and Total Synthesis of Hoshinolactam, an Antitrypanosomal Lactam from a Marine Cyanobacterium
摘要:
In the search for new antiprotozoal substances, hoshinolactam, an antitrypanosomal lactam, was isolated from a marine cyanobacterium. The gross structure was elucidated by spectroscopic analyses, and the absolute configuration was determined by the first total synthesis. Hoshinolactam showed potent antitrypanosomal activity with an IC50 value of 3.9 nM without cytotoxicity against human fetal lung fibroblast MRC-5 cells (IC50 > 25 mu M).
Stability, Reactivity, Solution, and Solid-State Structure of Halomethylzinc Alkoxides
作者:André B. Charette、Carmela Molinaro、Christian Brochu
DOI:10.1021/ja010837+
日期:2001.12.1
regarding the development of a Lewis acid-catalyzed cyclopropanation of allylic alcohols with bis(iodomethyl)zinc. Iodomethylzinc alkoxides can be formed by treatment of an alcohol with bis(iodomethyl)zinc. These species are not prone to undergo cyclopropanation at low temperature but the addition of a Lewisacid in catalytic amounts induces the cyclopropanationreaction. Using this procedure, we demonstrated
Catalytic Asymmetric Cyclopropanation of Allylic Alcohols with Titanium-TADDOLate: Scope of the Cyclopropanation Reaction
作者:André B. Charette、Carmela Molinaro、Christian Brochu
DOI:10.1021/ja0108382
日期:2001.12.1
titanium-TADDOLate complex was effective at catalyzing the cyclopropanation reaction of allylicalcohols in the presence 1 equiv of bis(iodomethyl)zinc. After initial optimization of the catalyst structure, excellent yields and enantiomeric ratios were obtained for 3-aryl- or 3-heteroaryl-substituted allylicalcohols (up to 97:3). Alkyl-substituted allylicalcohols gave modest yields and enantiomeric ratios (up
Enantioselective Cyclopropanation of Allylic Alcohols with Dioxaborolane Ligands: Scope and Synthetic Applications
作者:André B. Charette、Hélène Juteau、Hélène Lebel、Carmela Molinaro
DOI:10.1021/ja982055v
日期:1998.11.1
the conversion of allylicalcohols into the corresponding enantiomerically enriched cyclopropanes using bis(iodomethyl)zinc. A variety of chiral, nonracemic cyclopropylmethanols could be obtained according to this method. This methodology was extended with success to the cyclopropanation of unconjugated and conjugated polyenes and homoallylic alcohols. The cyclopropanation of allylic carbamates has also
In tandem reactions, cyclopropylcarbinols are obtained from allyloxylithium or -magnesium intermediates, generated in situ by alkylation of conjugated aldehydes, ketones, and esters as well as from allyl carboxylates or vinyloxiranes. Using this methodology, numerous fragrance ingredients and their precursors were efficiently converted to the corresponding cyclopropylcarbinols.
from α-substituted (homo)allyl alcohols. In tandem reactions, cyclopropyl carbinols are obtained from allyloxylithium or -magnesium intermediates, generated in situ by alkylation of conjugated aldehydes, ketones, and esters as well as from allyl esters and carbonates or vinyloxiranes. [¹] cyclopropanation - Barbier conditions - Grignard addition - alkyllithiumaddition - dibromomethane