The photolysis of 3,3-dimethyl-3H-pyrazoles derived from 2-diazopropane and acetylenic esters and nitriles leads in good yields to electrophilic cyclopropenes Starting from acetylenic ketones, only the 4-keto-3H-pyrazoles give acylcyclopropenes, the photolysis of the 5-keto-derivatives leading mainly to vinylketenes.
Accès au squelette triquinanique linéaire par l'intermédiaire de dérivés bicyclo [2.1.0] pentaniques. Synthèse totale d'un triquinane, le (±) hirsutène.
作者:Michel Franck-Neumann、Michel Miesch、Eric Lacroix、Bernard Mertz、Jean-Marc Ken
DOI:10.1016/s0040-4020(01)88514-8
日期:1992.1
The cycloaddition of enamines with electrophilic gem-dimethylcyclopropenes followed by solvolytic ring cleavage of the 2-amino bicyclo [2.1.0] pentane adducts, leads to gem-dimethylcyclopentene derivatives. These reactions are used as key-sequence for the synthesis of Hirsutene, a natural linear triquinane, starting from the cyanocyclopropene 18 and the diquinane enamine 15. The cis-anti-cis-anti-cis
Vinylcarbenes acycliques: reactions de cycloadditions intermoleculaires
作者:M. Franck-Neumann、C. Dietrich-Buchecker
DOI:10.1016/0040-4020(78)88422-1
日期:1978.1
3-dimethyl-3H-pyrazoles in unsaturated solvents leads in good yields and often with high stereoselectivity, to vinylcarbene cycloadducts. This direct synthesis of vinylcyclopropanes, vinylcyclopropenes and divinylcyclopropanes shows that acyclic vinyl carbenes are not necessarily intramolecularly stabilized. They can actually be trapped by olefins, acetylenes or dienes, depending on the carbene substituents. Cyano