Approach Toward the Total Synthesis of Griseoviridin: Formation of Thioethynyl and Thiovinyl Ether-Containing Nine-Membered Lactones through a Thioalkynylation−Macrolactonization−Hydrostannylation Sequence

Abstract

Synthesis of the lactone core 17 of 8-epi-griseoviridin is reported. Thioethynyl derivative 11 was easily prepared via an anionic coupling reaction between acetylenic compound 9 and sulfone 10. After desilylation of 11, saponification of the resulting hydroxy ester 12 followed by a Mitsunobu macrolactonization furnished the unusual triple-bond-containing nine-membered lactone 13 in 50% yield for the last two steps (39% after recrystallization). Stannylation under Magriotis conditions led to the pure regio- and stereocontrolled vinyltin 14 (80% yield). After a Sn/I exchange, palladium-catalyzed carbonylation delivered either the ester lactone 16 in 67% yield or the propargyl amide 17 in 65% yield. Synthesis of propargyl amide 17 of the lactone core of 8-epi-griseoviridin was achieved in 11.9% overall yield from commercial L-cystin dimethyl ester (nine steps).

Chemistry and Biology of the Streptogramin A Antibiotics

“…Ardisson's group reported preparation of a diastereomeric aminolactone (Scheme 34) [62] similar to that reported by Miller. The and permission has been granted for this version to appear in e-Publications@Marquette.…”

Synthesis of Macrocyclic Lactams and Lactones Containing Sulfur and Nitrogen

“…Макроциклом, содержащим лактамную группу, оксазольный и тиалактольный фрагменты, является гризеовиридин (74), относящийся к группе стрептогра-миновых антибиотиков широкого спектра действия, впер-вые выделенный из почвенных бактерий Streptomyces griseus и проявляющий in vitro активность к различным патогенным бактериям и грибам [42] (Схема 21). Ретросинтетический анализ молекулы 74 показывал возможность её получения из двух блок-синтонов 75 и 76, [43] хотя полный синтез еще не осуществлен.…”

Métodos de preparação de lactonas de anel médio

“…Assim, partindo de um derivado da L-(S)-cisteína, Ardisson et al 44 sintetizaram um intermediário avançado para a síntese da 8- A obtenção da unidade lactônica correspondente à entgriseoviridina, juntamente com um isômero, foi relatada pelo mesmo grupo 45 . A abordagem utilizada consistiu de uma ciclização redutiva de um dissulfeto intermediário.…”