2001 furan derivatives

furan derivativesR 0060

33 - 121Stereoselection in the Prins-Pinacol Synthesis of Acyltetrahydrofu-rans. — A detailed study on the stereochemistry of the title reaction ispresented. Nature of the alkene and size of the C3 substituent have little effect inthe reactions of acetals derived from syn allylic alcohols leading predominantlyto furan derivatives (II). In the anti series compounds (II) are obtained as majorproducts only when the C3 substituent is small and when the π nucleophileis a terminal vinyl group. A new model for prediction of the stereoselectionin the title reaction taking into account stereoelectronic effects of the allylicsubstituent and the extend of bonding in the Prins cyclization transition stateis proposed. — (COHEN, FREDERICK; MACMILLAN, DAVID W. C.;OVERMAN, LARRY E.; ROMERO, ALEX; Org. Lett. 3 (2001) 8, 1225-1228;Dep. Chem., Univ. Calif., Irvine, CA 92697, USA; EN)

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