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

Abstract

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- -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). 2-dialkylboryl-alkenes (9, 10), (E)-1-diethylamino-1-trimethylstannyl-2-dialkylboryl-alkenes (11, 12), (E)-1-methyl(phenyl)amino

Formation of Reactive π-Conjugated Frustrated N/B Pairs by Borane-Induced Propargyl Amine Rearrangement

“…We had prepared many of the P/B compounds 1 in a straightforward way by 1,1-carboboration of the alkynyl phosphanes Ar 2 PCCR 1 with boranes R 2 B­(C 6 F 5 ) 2 . , 1,1-Carboboration reactions of ynamines required special migrating groups and in view of the uncertainties of developing a suitable nitrogen analogue we decided to search for a principally different synthetic approach to the unsaturated N/B FLP systems 2 . This was achieved by a borane induced rearrangement of a bulky propargyl amine.…”