Determination of the absolute configurations of isotopically chiral molecules using vibrational circular dichroism (VCD) spectroscopy: the isotopically chiral sulfoxide, perdeuteriophenyl-phenyl-sulfoxide
摘要:
The (+) and (-) enantiomers of the isotopically chiral sulfoxide, perdeuteriophenyl-phenyi-sulfoxide, 1, have been synthesized by the reaction of the diastereomers of O-menthyl benzenesulfinate with C6D5MgBr. Their absolute configurations have been determined by comparison of the vibrational circular dichroism (VCD) spectra of (R)-1 and (S)-1, predicted using ab initio DFT, to the experimental VCD spectrum of 1. The absolute configuration of 1 is shown to be (S)(+)1(R)(-). This is the first application of VCD to the determination of the absolute configuration of an isotopically chiral sulfoxide. (c) 2008 Elsevier Ltd. All rights reserved.
The first total synthesis of (-)-graminin A is described. Key features of our synthetic approach involve a palladium-catalyzed asymmetric cyclization carbonylation of prochiral propargylic acetate, conversion of the orthoester product into methyl 4-oxo-3-furancarboxylate, and copper complex-mediated aldol condensation of (+)-gregatin B bearing a diene moiety. A new synthesis of (+)-gregatin B and the