منابع مشابه
Bridgehead enolates and bridgehead alkenes in a welwistatin model series.
Bridgehead metallation is possible in a ketone having the welwistatin skeleton, and this facilitates installation of the isothiocyanate function present in the natural product, and also enables synthesis of remarkable bridgehead alkenes.
متن کاملThe bonding situation in triethylchalcogenostiboranes - polarized single bonds vs. double bonds.
Triethylchalcogenostiboranes Et3Sb[double bond, length as m-dash]E (E = S , Se ) were synthesized and their solid state structures were determined. The Sb-Se bond length is the shortest ever reported. Short SbE contacts were not observed. According to quantum chemical calculations, the bonding situation in and is best described as a polarized Sb-E single bond.
متن کاملReactions of Diazomethane with Sulfonyl-activated Double Bonds
The cyclo-addition reaction of diazomethane with a,/3-unsaturated sulfones is described. Divinyl sulfone and phenyl vinyl sulfone give 1or 2-pyrazolines depending on the reaction conditions. cisand /rans-l,2-Bis(methylsulfonyl)ethene form pyrazolines, which on reaction with either triethylamine or excess of diazomethane lead to substituted pyrazoles. The addition of diazomethane to doüble bonds...
متن کاملReactions of Diazomethane with Sulfonyl-activated Double Bonds
The cyclo-addition reaction of diazomethane with a,/3-unsaturated sulfones is described. Divinyl sulfone and phenyl vinyl sulfone give 1or 2-pyrazolines depending on the reaction conditions. cisand /rans-l,2-Bis(methylsulfonyl)ethene form pyrazolines, which on reaction with either triethylamine or excess of diazomethane lead to substituted pyrazoles. The addition of diazomethane to doüble bonds...
متن کاملBridgehead enolate or bridgehead organolithium? DFT calculations provide insights into a difficult bridgehead substitution reaction in the synthesis of the polycyclic polyprenylated acylphloroglucinol (PPAP) nemorosone.
A computational study (B3LYP), of the metallation of a bridged ketone, an important step in the synthesis of a polycyclic polyprenylated acylphloroglucinol (PPAP), nemorosone, shows three energetically distinct structural possibilities for the lithiated intermediate. These findings, along with observations of the reactivity of the intermediates in bridgehead substitutions, suggest that differen...
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ژورنال
عنوان ژورنال: Pure and Applied Chemistry
سال: 1987
ISSN: 1365-3075,0033-4545
DOI: 10.1351/pac198759121613