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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

ChemInform Abstract Reaction of the propynyl ether (I) with trialkylboranes such as (II) with sterically non-demanding substituents leads to new oxaborolanes such as (III) in quantitative yield. In contrast, sterically demanding substituents lead to alkenes such as (IV). Products of this type are also formed in the reaction between (V) and (II). However, parts of this compounds are unstable and undergo exchange of alkyl groups between the stannyl and boryl moieties (no yields given).

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