Reaction of Dess–Martin periodinane with 2-(alkylselenyl)pyridines. Dehydration of primary alcohols under extraordinarily mild conditions
作者:Thanos Andreou、Jordi Burés、Jaume Vilarrasa
DOI:10.1016/j.tetlet.2010.02.002
日期:2010.4
Dess-Martin periodinane oxidizes very rapidly 2-pyridylseleno derivatives RR'CHCH2SePy in CHCl3 or CH2Cl2 and more chemoselectively than mCPBA. Tetravalent selenanes, RR'CHCH2Se(OAc)(2)Py, seem to be formed. Treatment of these intermediates with aqueous NaHCO3 gives rise to irreversible hydrolysis and elimination to terminal alkenes. As the OH/SePy exchange can be performed in minutes, the overall process is an exceptionally efficient procedure for the dehydration of primary alcohols. (C) 2010 Elsevier Ltd. All rights reserved.
Diastereoselective Intramolecular Carbolithiations of Stereodefined Secondary Alkyllithiums Bearing a Remote Alkynylsilane
secondary alkyl iodides bearing a remote alkynylsilane underwent intramolecularcarbolithiations triggered by an I/Li-exchange performed at −100 °C using t-BuLi (2.5 equiv). The resulting alkenyllithiums were stereoselectively converted to tetrasubstituted cyclopentane exo-alkylidenes. After Pd-catalyzed hydrogenation, cyclopentanes and cis-bicyclo[4.3.0]nonanes were obtained with stereocontrol of