Andrew John Gilby Baxter

Total synthesis of (±)-isoprosopinine B and (±)-desoxoprosopinine

The synthesis of the title compounds (10) and (16) in eleven and ten steps respectively from the imine (1) and 2-trimethylsilyloxycyclohexa-1,3-diene (2)via the azabicyclo-octanone (3) and the triol (5) illustrates a new general method for the preparation of the prosopis alkaloids.

Olivanic acid analogues. Part 1. Total synthesis of the 7-oxo-1-azabicyclo[3.2.0]hept-2-ene-2-carboxylate system and some related β-lactams

4-Allylazetidin-2-one, prepared from penta-1,4-diene and chlorosulphonyl isocyanate, has been used to synthesise the parent 7-oxo-1-azabicyclo[3.2.0] hept-2-ene-2-carboxylate system of the naturally occurring olivanic acids, using an intramolecular Witting reaction to construct the 2,3-double bond. Cyclisation of ketones derived from the 4-allyl grouping produced 3-substituted derivatives, while use of the azetidin-2-one prepared from hexa-1,5-diene and chlorosulphonyl isocyanate has given the homologous 8-oxo-1-azabicyclo[4.2.0]oct-2-ene system.

Synthesis of olivanic acid analogues: a facile route to 3-(2-pyrimidinylthio-) substituted derivatives

Abstract 3-(2-Pyrimidinylthio-) substituted olivanic acid analogues, with and without a C-6 hydroxyethyl substituent, have been synthesised in high yield using an intramolecular Wittig reaction followed by deprotection to afford zwitterions with high antibacterial activity.

A new synthesis of FPL 64176 and analogues: The discovery of benzoylpyrrole calcium channel activators with low nanomolar potency

Abstract Heavy metal assisted halogen displacement on 2-halobenzoylpyrroles (2 and 3) leads to a simple synthesis of FPL 64176 (1) and a variety of analogues (4–10). The difluoro derivative (4). EC50 1nM, and the amino linked analogue (7), EC50 2.7nM, are presently the most potent calcium channel activators known.

Synthesis of 7-oxo-1-azabicyclo[3.2.0]hept-2-ene-2-carboxylates: the olivanic acid ring system

The β-lactams prepared from penta-1,4-diene and cyclohexa-1,4-diene by reaction with chlorosulphonyl isocyanate can be readily converted into the 7-oxo-1-azabicyclo[3.2.0]hept-2-ene ring system, using an intramolecular Witting reaction to form the 2,3-double bond.

Synthesis of olivanic acid analogues. Preparation of 7-oxo-1-azabicyclo[3.2.0]hept-2-ene-2-carboxylates containing the 3-(2-acetamidoethenylthio) side chain

2-Acetamidoethenylthioesters have been prepared from 4-carboxymethylazetidin-2-one and cyclised via an intramolecular Wittig reaction to provide 3-(2-acetamidoethenylthio)-7-oxo-1-azabicyclo[3.2.0]hept-2-ene-2-carboxylates, closely related analogues of the naturally occurring antibiotic MM 13902 (1).

Synthetic studies in the piperidine alkaloid field. Part 1. The 2-azabicyclo[2.2.2]octan-5-one approach to prosopine

An approach to the synthesis of the Prosopis alkaloids utilising the Baeyer–Villiger reaction of methyl 2-benzyloxycarbonyl-5-oxo-2-azabicyclo[2.2.2]octane-3-carboxylate (6; R = CO2Me) is described. The boron trifluoride–ether catalysed cycloaddition to cyclohexadiene of methyl 2-(benzyloxycarbonylimino)acetate (8; R = CO2 Me), generated in situ from methyl N-benzyloxycarbonyl-2-methoxyglycinate, gave a mixture of bicyclic adducts (9) and (10). Oxymercuriation of (9) gave the alcohol (11; R = H), and subsequent oxidation gave the ketone (6; R = CO2Me). Baeyer–Villiger oxidations of (6; R = CO2Me or CH2·O2CPh) gave the lactones (14) and (15), respectively, and none of the desired lactone (7).

Participation of sulphonamide nitrogen in the rearrangement of the 2-azabicyclo[2.2.2]octane skeleton: an efficient synthesis of the 6-azabicyclo[3.2.1]octan-4-one system

Treatment of the 2-azabicyclo[2.2.2]oct-5-ene imino Diels–Alder adduct (2) with N-bromosuccinimide in aqueous dimethoxyethane gives the rearranged bromohydrin (4a), whose structure is confirmed by X-ray crystallographic analysis, and which serves as a precursor to the 6-azabicyclo[3.2.1]octane-4-one (7).