DESIGN OF [1,N]-AMBIPHILES BASED ON ZINCATE CARBENOID CHEMISTRY

Treatment of propargyl methanesulfonates, chlorides, and carbamates 4 with lithium triorganozincates 5 generated the corresponding propargyl ic alkynylzincates 6, which underwent an S(N)2'-type 1,2-ligand migrat ion to form allenylzinc intermediates 7. On treatment with electrophil es, 7 finally gave propargyl derivatives 8 in which both the nucleophi le and electrophile are bound tandem to the 1- and 3-position, respect ively. Similar reactions of homopropargyl analogues 15 generated (cycl opropylidene)alkylzinc intermediates 16, which further reacted with el ectrophiles to furnish methylenecyclopropanes 18 or 19. 5-Hexynyl tosy late 20 also afforded (cyclopentylidene)alkylzinc compound 21.