Highly efficient photochemical addition of tertiary amines to electron deficient alkenes. Diastereoselective addition to (5R)-5-Menthyloxy-2[5H]-furanone

Tertiary amines derived from pyrrolidines can be added very efficiently (is olated yields up to 94%) to (5R)-5-mentyloxy-2[5H]-furanone. The addition, which follows a radical chain mechanism initiated by a photoinitiated elect ron transfer (PET) from the tertiary amine to the excited aromatic ketone, occurs with a complete facial selectivity on the furanone ring. The method can be generalized to the addition of tertiary amines and N-protected secon dary amines to electron deficient alkenes. (C) 1999 Published by Elsevier S cience Ltd. Ail rights reserved.