Synthesis of 2- and 3-Stannolenes via Addition of Trimethyltin Alkoxides to 3-Diethylboryl-4-ethyl-1,1-dimethylstannole

✍ Scribed by Wrackmeyer, Bernd ;Klaus, Uwe ;Milius, Wolfgang

• Book ID: 102791688
• Publisher: Wiley (John Wiley & Sons)
• Year: 1995
• Tongue: English
• Weight: 827 KB
• Volume: 128
• Category: Article
• ISSN: 0009-2940
• DOI: 10.1002/cber.19951280705

✦ Synopsis

Trimethyltin alkoxides (2) react stereoselectively with 3-diethylboryl-4-ethyl-l,l-dimethylstannole (1) via addition of the Me3Sn group to C(2) to the C(2)=C(3) bond and a 1,2 shift of a n ethyl group from boron to C ( 3 ) to give the 2-stannolenes 3. The molecular structure of 3f' [R = (S)-2-Bu] was determined by single-crystal X-ray analysis, confirming the cis positions of the Et(R0)B and the Me3Sn group. These 2stannolenes 3 undergo, upon heating to ca. 80°C, facile rearrangement by irreversible allylic migration of the Et(R0)B group to the 3-stannolenes 4 in which the cis positions of the boryl and the stannyl group are retained. All 2-stannolenes (in contrast to the 3-stannolenes) are readily deprotoborylated to give the 3-stannolene 5. The structures of 3, 4, and 5 follow conclusively from lH-, llB-, 13C-, and llgSn-NMR spectra. The negative sign of the geminal coupling constants 2J(SnSn) was determined in the case of 3, 4, and 5 by 2D lgSn/lH heteronuclear shift correlations.