ON PENTAORGANYLSTIBORANE .3. REGIOSELECTIVE AND DIASTEREOSELECTIVE ADDITIONS OF ACETYLENIC AND ALLENIC ORGANOANTIMONY COMPOUNDS TO ALDEHYDES

The reaction of propargyl bromide (4a) with tributylstibine gave allen yltributylstibonium bromide (5), and its pentaorganylstiborane reacted with aldehyde to give homopropargylic alcohol (10a) exclusively in go od yield. However, the reaction of 1-bromo-2-butyne (4b) with tributyl stibine gave acetylenic stibonium bromide (6b), and its corresponding stiborane reacted with aldehyde to give allenic alcohol (9b) as major product. The reaction of 3-bromo-1-trimethylsilyl-1-propyne (4d) with tributylstibine also gave acetylenic stibonium bromide (6d), but the m ajor product of the reaction of its corresponding stiborane with aldeh yde was acetylenic alcohol (10d), and the regioselectivity was very hi gh in the presence of LiBr. Further, it was found that the allenic sti bonium bromide (12) was obtained by the reaction of 3-bromo-1-butyne ( 11) with tributylstibine. The corresponding stiborane (13) reacted wit h aldehyde to give acetylenic alcohol (14) exclusively in good yield, and the diastereoselectivity was moderately in favour of the threo iso mer in the presence of MgBr2. All of the reactions had good chemoselec tivity for aldehyde.