Application of Grignard reagents to the synthesis of tertiary methylamines via resin-bound oxyiminium ions

Organometallic chemistry on solid phase. An overview

Solid-phase organic synthesis (SPOS) is the most important method for the production of combinatorial libraries and with the development of high-throughput screening, libraries are widespread in pharmaceutical and agricultural chemistry. Amongst all the synthetic transformations successfully applied to solid phase, the use of organometallic reagents for the formation of a new carbon-carbon bond has been scarcely pursued. In this overview we collected the most recent examples of the use of organometallic reagents of Li, Mg, Cu, Zn, Si and B for C-C bond formation. The use of organometallic reagents in Pd-catalysed cross-coupling reactions was not reviewed. Highly basic organometallics as organo-lithium and -magnesium reagents have been more largely employed than cuprates and zincates, suggesting that several kinds of resins can withstand relatively strong reaction conditions.

Polymer-supported benzotriazoles as catalysts in the synthesis of tetrahydroquinolines by condensation of aldehydes with aromatic amines

Four polymer-supported benzotriazoles were prepared by linkage of 5-(hydroxymethyl)benzotriazole and benzotrizaole-5-carboxylic acid with Wang resin, Merrifield resin, and (monomethoxy)poly(ethylene glycol). The solid-phase and liquid-phase syntheses of tetrahydroquinolines were achieved by two-pair coupling reactions of aldehydes and aromatic amines using these polymer-supported benzotriazoles as the promoters. The ether-type benzotriazole prepared by loading 5-(hydroxymethyl)benzotriazole onto Merrifield resin turned out to be the catalyst of choice. Thus, a series of tetrahydroquinoline products were obtained in high purity by simple filtration, and the resin was recovered for reuse without loss of activity.