Pyrolysis of 1-alkylazetidinone derivatives: A versatile route toward electron-rich alkenes, C-1 allylation and/or homologation of aldehydes

摘要

1-Alkyl-3-phenoxy-beta-lactams have been synthesized by the standard Staudinger ketene-imine [2 + 2] cycloaddition. The corresponding beta-thiolactams have readily been obtained in good yields by thiation with Lawesson's reagent. Static pyrolysis (STP) as well as FVP of these beta-lactams and beta-thiolactams led essentially to stereoselective synthesis of Z-alkenes. The 3-allyloxy-1-alkyl-beta-lactams and beta-thiolactams have also been prepared and gave upon pyrolysis 4-pentenal derivatives. Pyrolysis of 1-alkyl-beta-lactams offers better yield than those reported from the corresponding 1-aryl derivatives, it also provides an easy access to the high energy electron-rich Z-alkenes and the synthetically important 4-pentenal.