M. Teresa Barros

The first synthesis of (-)-asperpentyn and efficient syntheses of (+)-harveynone, (+)-epiepoformin and (-)-theobroxide.

A generally applicable strategy for the synthesis of a range of polyoxygenated cyclohexane natural products has been developed. The enantioselective syntheses of (-)-theobroxide, a polyoxygenated cyclohexane natural compound with potent growth inducing properties in potato microtubers has been achieved via a 1,2 O-silyl migration between trans-hydroxyl groups and a remote hydroxyl directed epoxidation of an enone derived from quinic acid. A thus derived alpha-iodoenone was subjected to Stille coupling with tetramethylstannane to afford the first title compound. A similar strategy enabled a route to the complete asymmetric synthesis of the acetylenic phytotoxin (+)-harveynone. By selective reduction of (-)-theobroxide, (+)-epiepoformin was also prepared in enantiopure form and similarly, stereoselective reduction of (+)-harveynone completed the first enantioselective synthesis of (-)-asperpentyn, another natural compound with antimicrobial activity.

A synthesis of aziridines from α-iodoenones

Abstract Aziridines were prepared from α-iodocycloenones in very good yield, by a Michael addition/cyclisation (Gabriel–Cromwell) process employing a slight excess of primary amine and Cs 2 CO 3 as base at 95°C. Using chiral amines it was possible to prepare optically pure aziridines. The same method was also efficient for the synthesis of aziridines from acyclic α-halounsaturated compounds. 2-Oxoazabicycles reacted with several nucleophiles to afford α-heteroatom substituted cyclic enones in excellent yield.

An efficient transformation of quinic acid to shikimic acid derivatives

Abstract The synthesis of (−)-methyl shikimate and (−)-methyl 3- epi -shikimate and the 3-aminoshikimate derivative have been achieved via short and efficient routes from quinic acid.

The enantioselective total synthesis of epoformin and analogues

Abstract The enantioselective synthesis of epoformin, an antibiotic and cytotoxic natural compound, has been achieved via a remote hydroxyl directed epoxidation of an α,β-unsaturated ketone derived from quinic acid.

Total Synthesis of Saturated and Unsaturated di-trans-N-substituted Cyclam-based Macrocycles Through a Versatile Intermediate

Abstract A total synthesis of di-trans-N-substituted cyclam-type macrocycles through a versatile intermediate is described for the first time. This synthesis uses readily available low-cost commercial reagents. This synthesis was designed in such a way that the products and some intermediates could be selectively deprotected providing versatility both during the synthesis and for the utility of the final product. Thus, it should be possible to form cryptand molecules with trans bridges with good selectivity.

The alkylation of a novel acetal derived from (2R,3R)-(+)-tartaric acid: An unexpected rearrangement

Abstract The novel chiral bis -acetal dioxane 2a derived from (2 R ,3 R )-(+)-tartaric acid was shown to undergo an unexpected rearrangement upon treatment with lithium amide base to give the chiral dioxolane 3a in optically active form. Alkylation and aldol studies were performed on the diisopropyl ester of this dioxolane 3b .

The effect of DMSO on the borohydride reduction of a cyclohexanone: A formal enantioselective synthesis of (+)-epibatidine

Abstract An asymmetric synthesis of (+)-epibatidine is described which uses the increased stereoselectivity of a borohydride reduction induced by the presence of DMSO.

CHIRAL DITHIOLANE SULPHOXIDES : AN EFFICIENT STEREOSELECTIVE SYNTHESIS OF (R) AND (S)-3-BENZOYLOXY-2-BUTANONE

Abstract The effect of the addition of water on the asymmetric oxidation of an acyl dithiane and an acyl dithiolane has been studied. The use of enantiomerically pure dithiolane sulphoxides is demonstrated in a highly selective synthesis of (R)-3-benzoyloxy-2-butanone which depends upon a diastereoselective ketone reduction.

An application of quinic acid to the synthesis of cyclic homochiral molecules : a common route to some interesting carbocyclic nucleoside precursors

Abstract A cyclopentane derivative elaborated from (−)-quinic acid has been converted efficiently and stereoselectively into several cyclopentylamines, precursors to carbocyclic nucleosides which have previously been shown to be biologically interesting.

The mechanism of the Mitsunobu azide modification and the effect of additives on the rate of hydroxyl group activation.

Abstract The Mitsunobu azide modification has been studied by NMR using a hindered alcohol and the principle intermediates involved have been tentatively identi