SYNTHESIS OF 2-TRIBUTYLSTANNYL-1-ALKENES FROM 2-TRIBUTYLSTANNYL-2-PROPEN-1-YL ACETATE

2-Tributylstannyl-2-propen-1-yl acetate (2), which can be easily prepa red from ethyl propynoate (5), represents a useful precursor to a vari ety of 2-tributylstannyl-1-alkenes of general formula 1. Thus, treatme nt of 2 with complex organocopper species of general formula RCu.MgBrX .LiBr (4) (R = alkyl, aryl, benzyl, allyl) affords compounds 1 in fair to excellent yields. However, this procedure is unsuccessful for the preparation of 2-tributylstannyl-1,4-pentadiene (1e) and 2,3-bis(tribu tylstannyl)-1-propene (1g). Nevertheless, compound Ig contaminated by hexabutylditin (13) can be synthetized by palladium-catalyzed reaction between 2 and (tributylslannyl)diethylaluminum (15). The reactions of (E)-2-tributylstannyl-2-octen-1-yl acetate (22) with compounds 4h (R = i-Bu; X = Br) and 4b (R = Ph; X = Br) have been also investigated. T hese reactions, when carried out in THF solution, provide mixtures of two regioisomers of general formula 23 and 1, respectively, in which t he prevailing components are those derived from a gamma-substitution r eaction. Compound 23b, free of the corresponding regioisomer 1k, has b een synthetized in low yield by palladium-catalyzed cross-coupling rea ction between 22 and phenyltrimethylstannane (25). Moreover, two N-sub stituted derivatives of 3-amino-2-tributylstannyl-1-propene, i.e. comp ounds II and Im have been prepared by palladium-catalyzed amination of 2.