David J. Ager

The alkylation of menthyl hippurate and some related materials : a reinvestigation

Abstract Benzylation of chiral esters of N -acylglycines using various bases and additives was examined. No C -alkylation was observed with one equivalent of base. Diastereoselectivities were dependent on the amount of additive, the nature of the N -acyl group, and the chiral ester. A model to account for the degree and sense of the stereoselectivity is proposed.

Studies on the alkylation of dipeptide substrates

Alkylations of anions derived from dipeptides with a glycine at the C-terminus have been investigated. A hydrocarbon sedition in the N-terminal residue does impart some asymmetric induction. The use of a chiral ester derivative provides the potential for double asymmetric induction and good selectivity. With an aspartyl residue at the N-terminus, problems were encountered due to competing side reactions. The use of an azetidinone could circumvent some of these, but the observed induction was not high.

Development of methodology based on the use of the 7-oxabicyclo[2.2.1]heptanyl system for the preparation of carbohydrate derivatives

The 7-oxabicyclo[2.2.1]heptanyl system provides a rapid entry to carbohydrate derivatives in a stereoselective manner by virtue of the rigid framework. The formation of this bicyclic system through a Diels-Alder reaction of furan with a number of dienophiles is influenced by the substitution on the dienophile. Use of an anion stabilising group as a carbonyl equivalent has previously led to a ring opening reaction of the bicyclic system. However, anion chemistry can be used to functionalise the bicyclic system, and used for the introduction of a hydroxy group that allows, in turn, a method for the preparation of hexose derivatives

The effect of base and additive on the alkylation of methyl hippurate

Abstract Contrary to a published report, C-alkylation of methyl hippurate requires two equivalents of base. The choice of additive (TMEDA or HMPA) influences the result. Deuteration of the enolate gives results which depend on both the deuterium source and the nature of the additive.