Synthetic Studies Towards (+)‐Dihydroampullicin. Michael Addition of N‐Boc‐2‐(tert‐butyldimethylsiloxy)‐3‐methyl‐pyrrole to α‐Methylene Lactones.

Abstract The Michael addition of N -( tert -butoxycarbonyl)-2-( tert- butyldimethylsiloxy)-3-methyl-pyrrole ( 4 ) to several α-methylene lactones catalyzed by fluoride ions yielded the corresponding homologated products ( 26 – 30 ) with good yields. Application of this reaction to the sililoxy bicyclic lactone ( 5 ) allowed us to isolate the tricyclic lactone ( 26 ), a highly valuable intermediate in our synthetic strategy leading to the growth regulator (+)-Dihydroampullicin ( 1 ).