Ulrich Conrad Dyer

Stereospecific synthesis of the anaesthetic levobupivacaine

Abstract Enantiomerically pure (S)-Bupivacaine is synthesised from the chiral pool using cheap and readily available (S)-lysine. The key steps in this efficient synthesis include an oxidative de-amination and stereospecific ring closure to form the pipecolamide core structure.

Preparation of enantiopure 4-arylmandelic acids via a Pd/C catalysed Suzuki coupling of enantiopure 4-bromomandelic acid

Abstract A library of enantiomerically pure mandelic acid derivatives has been prepared using a palladium on carbon catalysed Suzuki reaction. The chirality was derived from enantiomerically pure 4-bromomandelic acid which was obtained by resolution with α-methylbenzylamine.

SYNTHESIS OF TRANS-FUSED 5,5 BICYCLIC LACTONES / LACTAMS AS TEMPLATES FOR SERINE PROTEASE INHIBITION

Abstract Efficient routes have been developed for the synthesis of the trans-lactone2, the trans-lactam3 and their 3-substituted analogues based upon cyclisation strategies using Mukaiyamas reagent. 3β-Allyl, thiophenyl and propyl lactones 5 inhibit chymotrypsin and human leucocyte elastase and are representative of a novel class of serine protease inhibitors.

A novel synthesis of tert-leucine via a Leuckart type reaction

An efficient synthesis of racemic tert-leucine from trimethylpyruvic acid using a Leuckart type reaction is described. A facile resolution of an intermediate with α-methylbenzylamine allows entry into either (R)-or (S)-tert-leucine.

Total synthesis of A putative triene intermediate in monensin biosynthesis, activated as a caprylcysteamine thiol ester

Abstract The total synthesis is reported, from a pool of optically pure starting materials, of a tritium labelled form of a putative intermediate in monensin biosynthesis, in which the terminal carboxyl group is activated as a caprylcysteamine thiol ester.

An efficient route to triene synthons for putative intermediates in polyether antibiotic biosynthesis

Current research to establish the late stages of polyether antibiotic biosynthesis via polyepoxide cyclization cascades, as formulated by Cane, Celmer, and Westley, requires the availability through synthesis of relevant putative triene intermediates. The development of practical synthetic methodology to one such triene system is reported in this paper. A synthesis of the triene building block (4) has been accomplished from inexpensive starting materials, using in a key step a modification of the Julia-Lythgoe olefination reaction. Thus the sulphone (8) was prepared in 14 steps from geranyl bromide, in an overall yield of 23%. The optically pure ester (9) was derived from meso-2,4-dimethylglutaric anhydride in four steps with an overall yield of 17%. The sulphone (8) was coupled efficiently with the ester (9), and the coupled product was subsequently transformed into the triene (4).