Borane complexes metal-alkyl

Complex 31 also catalyses the high-yield formation of linear alkylboranes from alkanes under thermal conditions [22]. Scheme 10 depicts the dehydro-genative coupling of pinacolborane 33 with n-octane 35. In this reaction, 1-oc-tylpinacolborane 36 was the only product to be detected. No borane derivatives from functionalization at the internal positions were observed. 2-Methylhep-tane and methylcyclohexane provided only alkylboranes from primary C-H bond functionalization. The high selectivity for the termini of alkanes is kineti-cally determined and results from a steric preference for formation of a linear metal-alkyl complex. 

The reactions of late transition metal complexes with H2 are usually explained by oxidative addition of H2 giving dihydride. However, in certain reactions of transition metal alkyls or acyls with H2 or boranes, involvement of <7-bond metathesis better accounts for the results. 

In 1998 Simpkins et al. reported that the metallation and alkylation of N-methylisoindoline-borane complex 122 with n-BuIi/5 provided products 123 in up to 94 6 er (Scheme 38) [88,89]. The mechanism of the reaction was established to involve an asynunetric deprotonation to give an organolithium which is configurationally stable at nitrogen but stereochemically labile with respect to the C-Li bond. 

Chiral phosphines are widely used as auxiliaries for various metal-catalyzed asymmetric reactions and can be prepared from stable phosphine-borane complexes. Secondary P-chiral phos-phine-boranes can be prepared by reductive lithiation of the corresponding tertiary phosphine-borane using LN (eq Likewise, P-chiral tertiary phosphine ligands can be produced by the reductive lithiation of phosphinite-boranes followed by alkylation, both proceeding with retention of configuration (eq 18). ... 

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