PD-CATALYZED ASYMMETRIC-SYNTHESIS OF ALLYLIC TERT-BUTYL SULFONES AND SULFIDES - KINETIC RESOLUTION OF THE ALLYLIC SUBSTRATE BY A CHIRAL PD-COMPLEX

The acyclic and cyclic allylic tert-butyl sulfones 3, ent-3, 11a, 11b and 15a-c of 89-98% ee were synthesized in 40-92% yield by a Pd-cataly zed reaction of the respective allylic acetates and carbonates rac-1a, rac-1b, rac-10a, rac-10b and rac-14a-c with LiO(2)St-Bu in the presen ce of the chiral ligands 2a, ent-2b and 12. Formation of the n-butyl s ulfones 13a and 13b of 95% ee was observed. Reactions of rac-1a and 1b /ent-1b with LiO(2)St-Bu in the presence of 2a and ent-2b, respectivel y, in THF under heterogeneous conditions were accompanied by a kinetic resolution of the allylic substrates. The faster reacting allylic sub strate and the preferentially formed sulfone had the same absolute con figuration. The allylic tert-butyl sulfide 17 of 92% ee was obtained i n 63% yield by the Pd-catalyzed reaction of rac-1b with Me(3)SiSt-Bu i n the presence of ent-2b. (C) 1998 Elsevier Science Ltd. All rights re served.