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Highly diastereoselective synthesis of bicyclo(4.2.0)octanone derivatives by the (2+2) photocycloaddition of chiral cyclohexenonecarboxylates to ethylene


, : Highly diastereoselective synthesis of bicyclo(4.2.0)octanone derivatives by the (2+2) photocycloaddition of chiral cyclohexenonecarboxylates to ethylene. Tetrahedron Letters 45(41): 7621-7624

The diastereoselective (2+2) photocycloaddition of a cyclohexenonecarboxylate containing (-)-8-(4-nitrophenyl)rnentbyI as a chiral auxiliary to ethylene gave the photocycloadduct, a bicyclo(4.2.0)octanone derivative, with a high degree of diastereoselectivity. A photoreaction, conducted in CH2Cl2, at -78degreeC gave the corresponding photocycloadduct in 88% de. In the presence of Ti(OR)4 or Me3SnCl, the diastereoselectivity was increased up to 92% de. Copyright 2004 Elsevier Ltd.

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