Synthesis of hexadeuterated 23-dehydroxybrassinosteroids

Synthetic Aspects of Brassinosteroids

“…Available from the aldehyde (6) in two steps, disubstituted olefin (52) reacted with acetonitrile oxide to give a mixture of the cycloadducts (53) and (54). Hydride reduction of the main isomer (53) led to amino alcohol (55), the primary hydroxyl group of which was removed to give compound (56).…”

“…Its coupling with the labeled side-chain synthon (111) led to a diastereomeric mixture of propargylic alcohols (112). The cleavage of the epoxy ring in (115) proceeded with the formation of the product (117) A convergent synthetic approach to labeled BS developed by Khripach et al [55,56] made use of a side-chain synthon (123) already containing both a required C-24 stereocenter and all the deuterium atoms. Partial hydrogenation was effected over P-2 nickel catalyst in the presence of ethylenediamine.…”

“…The above approach to the side-chain construction in combination with traditional chemical methods of BS cyclic part functionalization was utilized for the preparation of hexadeuterated BS (127-129) (Figure 6.2) [55,56].…”

Synthesis of deuterium‐labeled (24R)‐methyl brassinosteroids

“…Mp 148-1501C (petroleum ether/EtOAc). (13) The title compound was obtained from enone 9 in 76% yield according to the procedure described for the preparation of ([26-2 H 3 ]epicastasterone) (12). Mp 96-981C (petroleum ether).…”

“…10 This compound proved to be useful for biochemical and physiological investigations, but because of its relatively low isotopic purity (82%) it could not be used in some experiments. Based on the experience we have gained in brassinolide biosynthetic studies, [11][12][13][14][15] labeling the terminal part of the steroidal side chain was considered as an appropriate solution of the problems connected with low isotopic purity. The present work is an extension of our studies 16 toward synthesis of labeled brassinosteroids for biochemical and other biological applications and deals with the preparation of [26-2 H 3 ]epibrassinolide and its biosynthetic precursors.…”