- Microwave induced selective enolization of steroidal ketones and efficient acetylation of sterols in semisolid state
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Under microwave irradiation steroidal enones, more specifically, position three carbonyls were efficiently and selectively converted to the corresponding enol acetates in the presence of additional enolizable carbonyl functions at other positions, using acetic anhydride and a catalytic amount of toluene-p-sulfonic acid. Acetylation of hydroxyl groups of the sterols, including those at the hindered positions, was near quantitative. Strictly anhydrous conditions were not a pre-requisite for acetylation and the reaction system easily tolerated up to 10% (v/v) moisture.
- Marwah, Padma,Marwah, Ashok,Lardy, Henry A.
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p. 2273 - 2287
(2007/10/03)
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- Regioselective esterification of polyhydroxylated steroids by Candida antarctica lipase B
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The regioselectivity of Candida antarctica lipase B towards the acetylation of polyhydroxylated steroids has been systematically investigated. The enzyme showed a marked preference for the alcoholic moieties on the A ring and: on the steroidal side chain, making it possible the selective acylation at the positions 3 or 21 of polyhydroxy steroids. Acylation with the synthetically useful esters chloroacetate and levulinate was also accomplished, whereas esterification with benzoate and pivaloate was unsuccessful.
- Bertinotti, Anna,Carrea, Giacomo,Ottolina, Gianluca,Riva, Sergio
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p. 13165 - 13172
(2007/10/02)
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- Pregnane and Pregnane Glycosides from Trachelospermum liukiuense
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Cortexone and three new bisdesmosidic glycosides of teikagenin were isolated from Trachelospermum liukiuense, together with five glycosides alredy known in Trachelospermum asiaticum.The new glycosides have D-digitalose linked to the 20-OH as well as to the 3-OH.Keywords: Trachelospermum; Apocynaceae; pregnane; cortexone; teikagenin; 20S,5α-pregn-6-en-3β,17α,20-triol; teikagenin 3,20-bis-O-digitaloside; teikaside
- Abe, Fumiko,Yamauchi, Tatsuo
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- New Synthesis of the Corticosterone Side-Chain
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Condensation reactions between azlactone 2 and 17-ketosteroids 1 followed by opening of the azlactone ring with sodium methanolate yields methyl 20-benzoylamino-17(20)-pregnen-21-oates 6.Reduction of the ester and subsequent hydrolysis produce compounds with the corticosterone side-chain as well as a ring-closed product of new type.
- Solyom, Sandor,Szilagyi, Katalin,Toldy, Lajos
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p. 153 - 160
(2007/10/02)
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