Pectenotoxin-2 synthetic studies. 1. Alkoxide precoordination to [Rh(NBD)(DIPHOS-4)]BF(4) allows directed hydrogenation of a 2,3-dihydrofuran-3-ol without competing furan production

[reaction: see text] The alkoxide-directed hydrogenation shown is reported as a key step in a concise synthesis of a fully functionalized precursor to the C29-C40 F/G sector of pectenotoxin-2.     

Malaria chemotherapy and the "kaleidoscopic" organisation of biomedical research during world war II

The paper describes the organisational and scientific evolution of the US antimalarial program during World War II. This program screened some 14,000 compounds for antimalarial activity, selected atabrine as the drug of choice in 1943, and later identified chloroquine as a superior compound. It became, arguably, the largest biomedical research effort of the first half of the twentieth century, involving chemical and pharmaceutical companies, diverse university researchers, and non-profit and government laboratories. Beyond scientific research, the innovations of the wartime antimalarial program were chiefly in three areas, communication, scale and administration. The program drew on resources - intellectual, material and organisational - created in Germany by researchers at Bayer, and in the US by the Rockefeller Foundation and Institutes. The paper examines the antimalarial program as one of the formative models for later programs such as the National Institutes of Health. This account supports the claim that wartime work was essential to the development of NIH, if only because the confused and faltering structures of the early war years, 1939-1943, do not suggest that all the organisational infrastructure for large scale, multi-centre co-operative research was in place prior to World War II.     

A vinyl sulfone-mediated diels-alder approach to the fully regiocontrolled elaboration of 4,5-disubstituted 2- and 3-cyclohexenones

Reported here is a scheme which enables one to prepare independently 4,5-disubstituted 2- or 3-cyclohexenones where the nature of the pendant sidechains can be widely varied.     

Synthesen von Dibenzo[b,e][1,4]dioxin-2,3-chinonen,einschliesslich der Ecklonochinone A und B sowie der Isoecklonochinone A und B

Syntheses of Dibenzo[b,e][1,4]dioxin-2,3-quinones Including the Ecklonoquinones A and B and the Isoecklonoquinones A and B Oxidation of monomesyloxy-substituted pyrocatechols with MnO₂ in toluene using phase-transfer conditions leads in high yield to monomesyloxy-substituted dibenzo[b,e][1,4]dioxin-2,3-quinones with loss of one mesyloxy group. In this way, ecklonoquinone A ( 2 ), ecklonoquinone B ( 3 ), isoecklonoquinone A ( 43 ), and isoecklonoquinone B ( 44 ) were prepared. Their structures are based on X-ray analyses of ecklonoquinone-A leucoacetate ( 45 ) and the mesyloxy-substituted quinone 20 . The reddish-violet dibenzodioxin-diquinone 49 was prepared from an intermediate of the iso-series. The parent compound 1 has been synthesized in yields better than 50% from pyrocatechol and methyl 2,5-dioxo-2,5-dihydrobenzoate as oxidant and 2-methoxypyridin as catalyst. To rationalize the specific effect on the dimerisation step of the mesyloxy group, the intermediacy of 1,4-quinone monoacetals is proposed. This also applies to a proposed biogenetic scheme.