Mono- and bishomobenzotropones. 1. Synthesis and nuclear magnetic resonance spectra of 2,3-benzo-6,7-monohomotropone and 2,3-benzo-trans-4,5:6,7-bishomotropone
Using dimethylsulfoxonium methylide as the methylene transfer reagent, 2a,8b-dihydrobenzo[b]cyclobute[d]pyran-3-ones were converted into 2,2'-biphenol derivatives as major products and dihydrodibenzofurans as minor products. The reaction mechanism was extrapolated from a deuteration experiment with CD2=S(O)(CD3)2.
Diastereoselective asymmetric cyclopropanation of (S)-(+)-α-(diethoxyphosphoryl)vinyl p-tolyl sulfoxide
作者:Wanda H. Midura、Jerzy A. Krysiak、Marian Mikołajczyk、Michał W. Wieczorek、Wiesław R. Majzner
DOI:10.1039/a801299g
日期:——
The title sulfoxide 1 reacts with fully deuterated dimethylsulfoxonium methylide, diphenylsulfonium isopropylide and diphenyldiazomethane to form the corresponding cyclopropanes 4 as single diastereoisomers; the chirality of the cyclopropane (+)-4c obtained from 1 and diphenyldiazomethane is (SS,SC) as determined by X-ray diffraction analysis; based on experimental data, the steric course of the asymmetric cyclopropanation is proposed.
AbstractThe mass spectrometric behaviour of four 2,3‐dihydro‐1‐benzofuran‐3‐acetic acids has been studied in detail with the aid of exact mass measurements, linked scans, collisionally activated decomposition, mass analysed ion kinetic energy spectra and labelling experiments. Unusual fragmentation pathways are emphasized for which mechanisms are proposed.