ISSN:
0009-2940
Keywords:
Silanes, tetra-1-alkynyl-
;
Germanes, tetra-1-alkynyl-
;
1,1-Ethyloboration, intermolecular
;
1,1-Vinyloboration, intramolecular
;
Spirosilanes
;
Spirogermanes
;
Protodeborylation
;
Transition metals, η41-complexes of
;
Chemistry
;
Inorganic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Organosubstituted 1,1′-Spirobisiloles and 1,1′-Spirobigermoles by Fourfold Organoboration of Tetra-1-alkynylsilanes and -germanes[1]Si(C≡CR)4 [R=Me (A), R=Ph (B), R=SiMe3 (C)] and Ge(C≡CR)4 [R=Me (D), R=Ph (E)] react with Et3B by twofold intermolecular ethyloboration and twofold intramolecular vinyloboration to form the organo-substituted 5-sila(germa)spiro[4.4]nonatetraenes , R=Me: 1a, R=Ph: 1b; M=Ge, R=Me: 2d, R=Ph: 2e] via the mono-and bisethyloboration compounds 3 or 4 (e.g. 3b, 4c) with different rates: Ge 〉 Si; Me 〉 Ph. For comparison, compounds Sn(C≡CR)4 [R=Me (F), R=Ph (G)] react with Et3B in the absence of a solvent to mixtures of various spirotin compounds (5f, 5g, 6f, 8f, 9g, 10g, 11g) of which only 9g (R=Ph) corresponds to the spirosilanes and -germanes. This is the result of effective competition between intramolecular and intermolecular organoboration in the case of the tetra-1-alkynyltin compounds. The protodeborylation of 1a, b and 2d, e with MeCO2H leads to 12a, b and 13d, e, respectively. 12a isomerises by UV irradiation to allyl isomers 12a′. From 12a with 2 equiv. of maleic anhydride the 1:2 addition compound 14a is obtained, the autaddition of 12a, d leads to 15a, d. Spiro compound 12a reacts with (OC)5Fe or CpCo(C2H4)2 to give the cyclodiastereomeric η41-complexes [(OC)3Fe]2-12a (16a1-a4; X-ray structure analysis of meso- 16a1), (OC)3Fe-12a (17a) and (CpCo)2-12a (18a1-a4). - All products were characterized by multinuclear NMR, including measurements of the coupling constants 1J(13C13C), 2J(29Si29Si), nJ(29Si13C) and nJ(119Sn13C).
Additional Material:
2 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/cber.19931260617
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