Calcium Hydride Insertion Reactions with Unsaturated C-C Bonds

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Abstract

The dimeric β-diketiminato calcium hydride, [(BDI)CaH]2 (BDI = HC{(Me)CN-2,6-i-Pr2C6H3}2), reacts with terminal alkenes to provide the corresponding alkyl derivatives. With 1-octene, 3,3-dimethyl-1-butene, 3-phenyl-1-propene, and 4-phenyl-1-butene, the ultimate products are dimeric alkyl species, which form sequentially via dinuclear calcium hydrido-alkyl intermediates. Reaction of diphenylacetylene with [(BDI)CaH]2 provides a tetra-calcium complex in which a stilbene dianion bridges symmetrically between two hydrido-bridged bis-β-diketiminato calcium units, while treatment with trans-stilbene yields a dicalcium benzyl-hydride derivative, [{(BDI)Ca}2(H)(PhCHCH2Ph)]. Reaction of [(BDI)CaH]2 and 1,5-hexadiene has previously been observed to provide facile 5-exo-trig cyclization to calcium cyclopentylmethyl derivatives. In contrast, analogous reaction with 1,7-octadiene provides exclusive intermolecular insertion to yield a dimeric open chain calcium oct-7-en-1-yl derivative. Reaction with the internal alkene, norbornene, enables the identification of a highly reactive dinuclear calcium norbornyl-hydride. The greater basicity of the calcium secondary alkyl species is emphasized by the subsequent isolation of a product of intramolecular deprotonation of a BDI iso-propyl methyl substituent.

Original languageEnglish
Pages (from-to)351-360
Number of pages10
JournalOrganometallics
Volume38
Issue number2
Early online date26 Dec 2018
DOIs
Publication statusPublished - 28 Jan 2019

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Organic Chemistry
  • Inorganic Chemistry

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