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W I D E S P R E A D ACCEPTANCE of deet (N,N-diethylrn-toluamide), a personal-use insect repellent (47) that is effective against a broad spectrum of biting arthropods (including the yellow fever and common malaria mosquitoes), led us to prepare compounds related to it. To find a better repellent, or possibly, one that might be superior against some of the insect species repelled by deet, we synthesized several hundred compounds for biological

Adirubine (1a), the first example of a new series of carboxy-alkaloids with the Corynanthe skeleton, has been isolated from Adina rubescens and its structure determined from chemical and spectral data.

Measurements and related analyses of the electron temperature and electron number density in an atmospheric pressure laminar thermal boundary layer adjacent to a cooled wall are described. The analyses proceed from consideration of the coupled electron continuity and electron energy equations with boundary conditions appropriate to NaK seeded argon. It is shown that the theoretical results can be interpreted in terms of three characteristic lengths:δ, the thermal boundary layer thickness, lE, the characteristic length for electron energy exchange, and lI, the characteristic length for ionization. Electron temperature profiles were measured experimentally in the boundary layer described above using a spectroscopic technique, and electron number density profiles were measured using a small traversing probe developed by the authors. The experimental results, obtained for various values of the lengths lE and lI, were found to be in good agreement with the theory.

Treatment of tabersonine with refluxing acetic acid under nitrogen yielded a new base, allocatharanthine (VI), and the derived (VII), but failed to produce detectable quantities of (±)-catharanthine or pseudocatharanthine, nor did similar treatment of stemmadenine afford any of these compounds.

The absolute stereochemistry at C-3 and C-15 in vincoside (1) has been established by a chemical correlation with corynantheine (11).

Tetrahydrosecodine (IVb) has been synthesised, and shown to be present in Rhazya orientalis by isotopic dilution analysis.