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1‐Boraadamantane: Reactivity Towards Di(1‐alkynyl)silicon and ‐tin Compounds: First Access to 7‐Metalla‐2,5‐diboranorbornane Derivatives
Author(s) -
Wrackmeyer Bernd,
Milius Wolfgang,
Klimkina Elena V.,
Bubnov Yuri N.
Publication year - 2001
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/1521-3765(20010216)7:4<775::aid-chem775>3.0.co;2-v
Subject(s) - intramolecular force , chemistry , reactivity (psychology) , tin , disilane , substituent , intermolecular force , nuclear magnetic resonance spectroscopy , medicinal chemistry , stereochemistry , silicon , crystallography , molecule , organic chemistry , medicine , pathology , alternative medicine
1‐Boraadamantane ( 1 ) reacts with di(1‐alkynyl)silicon and ‐tin compounds 2 (Me 2 M(C≡CR) 2 : M=Si; R=Me ( a ), t Bu ( b ), SiMe 3 ( c ); M=Sn, R=SiMe 3 ( e )) in a 1:1 ratio by intermolecular 1,1‐alkylboration, followed by intramolecular 1,1‐vinylboration, to give siloles 5 a–c and the stannole 5 e , respectively, in which the tricyclic 1‐boraadamantane system is enlarged by two carbon atoms. Owing to the high reactivity of 1 , a second fast intermolecular 1,1‐alkylboration competes with the intramolecular 1,1‐vinylboration as the second major step in the reaction if the substituent R at the C≡C bond is small ( 2 a ) and/or if the M−C≡ bond is also highly reactive, as in 2 d (M=Sn, R=Me) and 2 e (M=Sn, R=SiMe 3 ). This leads finally to the novel octacyclic 7‐metalla‐2,5‐diboranorbornane derivatives 8 a, 8 d , and 8 e , of which 8 e was characterized by X‐ray analysis in the solid state. 1,1,2,2‐Tetramethyldi(1‐propynyl)disilane, MeC≡C−SiMe 2 SiMe 2 −C≡CMe ( 3 ), reacts with 1 to give mainly a 1,2‐dihydro‐1,2,5‐disilaborepine derivative 9 and the octacyclic compound 11 , which is analogous to 8 a but with an Me 4 Si 2 bridge. All new products were characterized in solution by 1 H, 11 B, 13 C, 29 Si, and 119 Sn NMR spectroscopy. For 8 and 11 , highly resolved 29 Si and 119 Sn NMR spectra revealed the first two‐bond isotope‐induced chemical shifts, 2 Δ 10/11 B( 29 Si) and 2 Δ 10/11 B( 119 Sn) respectively, to be reported.