Aminoethynyl‐silanes, ‐germanes and ‐stannanes: novel organometallic‐substituted enamines via 1,1‐organoboration

The reactions of diethylaminoethynyl(trimethyl)silane (1), bis(diethylaminoethynyl)methylsilane (2), diethylaminoethynyl(trimethyl)germane (3), dimethylaminoethynyl(triethyl)germane (4), diethylaminoethynyl(trimethyl)stannane (5) and methyl(phenyl)aminoethynyl(trimethyl)stannane (6) with trialkylboranes [BEt 3 (7b), BPr 3 (7c), B i Pr 3 (7d) and 9‐alkyl‐9‐borabicyclo[3.3.1]nonanes 9‐Me‐9‐BBN (8a) and 9‐Et‐9‐BBN (8b)] were studied. The alkynes 1 and 2 did not react even with boiling BEt 3 , whereas the reactions of 3–6 afforded mainly novel enamines [( E )‐1‐amino‐1‐trialkylgermyl‐2‐dialkylboryl‐alkenes (9, 10), ( E )‐1‐diethylamino‐1‐trimethylstannyl‐2‐dialkylboryl‐alkenes (11, 12), ( E )‐1‐methyl(phenyl)amino‐1‐trimethylstannyl‐2‐dialkylboryl‐alkenes (13, 14)]. This particular stereochemistry is unusual for products from 1,1‐organoboration reactions, indicating a special influence of the amino group. The starting materials and products were characterized by multinuclear magnetic resonance spectroscopy ( 1 H, 11 B, 13 C, 15 N, 29 Si, 119 Sn NMR). Copyright © 2003 John Wiley & Sons, Ltd.