James Andrew Ramsden

The synthesis of S 18986, a chiral AMPA receptor modulator, via catalytic asymmetric hydrogenation

Abstract The asymmetric hydrogenation of a dihydropyrrolo-benzothiadiazine dioxide 1 with a diphosphine ruthenium diamine catalyst has been used to synthesize the AMPA receptor positive modulator tetrahydropyrrolo-benzothiadiazine dioxide 2 (S 18986) in high enantiomeric excess. The use of factorial experimental design led to significant improvements in the process parameters and improved enantioselectivity.

On the economic application of DuPHOS rhodium(I) catalysts: a comparison of COD versus NBD precatalysts

Abstract The effectiveness of cyclooctadiene and norbornadiene precatalysts of the type [Rh(DuPHOS)(diolefin)]BF 4 in catalytic asymmetric hydrogenation of various prochiral olefins has been examined. In some of the systems studied, the NBD complex gave rise to the catalytically active species more rapidly than the corresponding COD complex, as expected. However, as catalyst loadings were reduced to levels more conducive to economic manufacture, the difference between the use of COD and NBD precatalysts became increasingly insignificant. This was conveniently highlighted by the formation of low enantiomeric excess products upon using an equimolar mixture of ( S , S ) and ( R , R ) precatalysts, bearing COD and NBD respectively. With other substrates, the system displayed no induction time for either precatalyst and identical reaction profiles were observed.

A novel asymmetric route to 2-amino-1,2,3,4-tetrahydronaphthalenes

Abstract A novel asymmetric route to 2-amino-1,2,3,4-tetrahydronaphthalenes has been demonstrated starting from phthalimidovinylglycinol (PVG). Functionalisation of PVG via Heck reaction, olefin hydrogenation and cyclisation provides the title products.