Tributylphosphine, reactions, carbon disulfide

Nucleophilic Attack at Carbon. - Rate constants for the forward and reverse formation of the tributylphosphine - carbon disulfide adduct, Bu3P -CS2, have been determined in a range of solvents. The forward reaction constant shows little variation with solvent, whereas the reverse reaction constant... 

Depending on the reaction conditions, carbon disulfide is either simultaneously attacked on sulfur and carbon or exclusively on sulfur. Alkyllithiums show strictly thiophilic behavior toward the CS2 adducts with tributylphosphine and bis(dimethyl-amino)methylene. On the other hand, 2-oxepanethione ( -thionocaprolactone) and related thionolactones obey "carbophilic" reactivity toward organolithiums. ... 

Polymer-bound reagents have also been used. The synthetically important Weinreb amides [RCON(Me)OMe, see 16-82] can be prepared from the carboxylic acid and MeO(Me)NH HCl in the presence of tributylphosphine and 2-pyridine-A -oxide disulfide. Di(2-pyridyl)carbonate has been used in a related reaction that generates amides directly. The reaction of a carboxylic acid and imidazole under microwave irradiation gives the amide. Microwave irradiation of a secondary amine, formic acid, 2-chloro-4,6-dimethoxy[l,3,5]tria-zine, and a catalytic amount of DMAP (4-dimethylaminopyridine) leads to the formamide. ° Ammonium bicarbonate and formamide converts acids to amides with microwave irradiation. Lactams are readily produced from y- or 8-amino acids, for example. 

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