Synthesis of labelled epibrassinolide containing two deuterium atoms in a position which is not subjected to isotopic exchange is reported. Key transformations include preparation of 6,7-seco steroidal diacid, its cyclization to a cyclic anhydride followed by a regioselective reduction with NaBD 4 . The obtained [7, H 2 ]epibrassinolide can be used in biochemical experiments when the loss of isotopic label should be avoided.
The radical oxidation of 14α-hydroxy steroids with various functional groups at C-17 was studied. Lead tetraacetate and ceric ammonium nitrate were used as oxidizing agents. It was shown that reactions of this type afforded complex mixtures of compounds. However, the radical oxidation of 14α-hydroxy-17-oxo steroid (lead tetraacetate version of the hypoiodite reaction) proceeded smoothly with formation of the 13,14-secosteroid in up to 85% yield. The structure and conformation of the formed 13α-iodo-3α,5-cyclo-13,14-seco-5α-androst-5-ene-14,17-dione was determined by X-ray analysis.
2002steroids steroids U 0300
-239Radical Oxidation of 17-Functionalized 14α-Hydroxy Steroids.-Radical oxidation of 14α-hydroxy steroids possessing various functional groups at C-17 affords complex mixtures. At least partly these mixtures are the result of decomposition of the rings A and B. Thus, the more stable 3,5-cyclo derivatives (VIII) and (XII) are prepared and subjected to oxidation. The most promising result with regard to the synthesis of 13,14-secosteroids and yield is obtained with LTA/I 2 oxidation of 3,5-cyclo-17-oxo compound (XII). The structure and conformation of seco-compound (XIII) are determined by X-ray analysis. -(KHRIPACH, VLADIMIR A.; ZHABINSKII, VLADIMIR N.; KOTYATKINA, ANNA I.; FANDO, GALINA P.; ZHIBURTOVICH, YULIYA Y.; LYAKHOV, ALEXANDER S.; GOVOROVA, ALLA A.; GROEN, MARINUS B.; VAN DER LOUW, JAAP; DE GROOT, AEDE; Collect.
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