Organoborierung von Alkinylstannanen XXIII. Zur Reaktion einiger C-Funktionell substituierter Alkinylstannane mit Triethylboran und B-Alkyl-9-borabicyclononanen

Article abstract of DOI:10.1016/0022-328X(88)80133-5

The influence of functional groups in R¹ on the course of the organoboration reaction of alkynylstannanes 1, Me3SnC<*>CR¹ (R¹=OEt (a), 3-Methoxyphenyl (b), 2-Pyridyl (C)) has been studied.The reactions of 1 with triethhylborane (2) yields the products (4), with the stannyl and boryl groups always in the cis-position.In the case of reaction between 2 and 1c it has been observed for the first time that the organoboration is followed by a Me/Et exchange between the tin and the boron atoms (4d).A possible mechanism is described.The alkyne 1c reacts stereoselectively with the B-alkyl-9-borabicyclo<3.3.1>nonanes, 3 (alkyl=Me (a) , Et (b) i-Pr (c)), to give the compounds 5a, b, c in which the bicyclic system has been enlarged by one carbon atom, with the stannyl- and boryl-groups remaining in the cis-positions. 1H, 11B, 13C, 119Sn NMR spectroscopy, and analytical data support the proposed structures of compounds 4 and 5.