Carbon monoxide, reaction with organoborane

In Scheme 9.1 there are described reactions of organoboranes with cyanide ion, lithiodichloromethane, and dichloromethyl methyl ether. Compare the structures of these reagents and the final reaction products from each of these reagents. Develop a general mechanistic outline with encompasses these reactions, and discuss the structural features which these reagents have in common with one another and with carbon monoxide. 

Reductive carbonylation and alkylation of imines.3 This cobalt carbonyl catalyzes a reaction of imines with organoboranes and carbon monoxide that results in amides. / -Keto amides are obtained from a-keto imines by this reaction. 

The reaction of organoboranes with carbon monoxide is one of the most versatUe reactions among synthetic applications of organoboranes. Triorganoborane-CO adducts, although not stable enough to be isolated, are isoel Aronic with cyano-trialkylborates. A wide variety of primary, secondary and tertiary alcohols, aldehydes, and ketones have been synthesized by this reaction. Since such reactions have been extensively reviewed only recent progress is presented here. 

TriaikykarUnols from trialkylhoraites. Trialkylcarbinols have been prepared by the reaction of trialkylboranes with carbon monoxide in diglyme followed by oxidation with hydrogen peroxide (equation 1). See 2. 60. The method has the disadvantage that at the temperature required isomerization of organoboranes can be significant. 

Lithium trimethoxyaluminum hydride [1,625, before references]. The reagent greatly enhances the reaction of carbon monoxide with organoboranes.4 The reaction can... 

Some interesting developments concerning C-C bond formation using organoborane coupling reactions have been made. 9-Alkyl-9-BBN derivatives (144) react with aryl and benzyl halides in the presence of transition metal catalysts and carbon monoxide to give... 

These versatile reactions, commonly referred to as Stille and Suzuki couplings, respectively, are performed with organostannanes or organoboranes as nucleophiles and are tolerant to most functional groups. Ketones are obtained if carbon monoxide is present in the Stille reaction. This gives the possibility to label an aromatic methyl ketone in two different positions by the use of either [ C] carbon monoxide or [ C] methyl iodide, as shown in O Fig. 41.22 (Andersson et al. 1995 Andersson and Langstrom 1995a, b). 

SCHEME 5.4 The reaction of organoboranes with carbon monoxide and cyanide ion. 

The incorporation of isotopic labels via organoboron chemistry has been the subject of previous communications from Kabalka and co-workers, and two further examples have been reported this year. For example, the preparation of primary alkylamines by the reaction of organoboranes with NH4OH, described in 1981, has now been used to give N-labelled primary amines, and C-labelled carboxylic acids are readily prepared from the reaction of organoboranes with C-enriched carbon monoxide. ... 

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