Solasodine reduction

A O-Diacetyldihydropseudosolasodine (12a) gave the epimeric pyrrolidines (13) on treatment with bromine. When N-bromosuccinimide was used as oxidant, the ketone (12b) and the pyrrolidine (14) were also formed.17 The WolfF-Kishner reductions of solasodenone (9b) and of the epimeric 4,5 -dihydro-analogues have been reported.18 Solasodine gave the expected 5a,6-epoxide on treatment with perbenzoic acid.19 The preparation of an intermediate in the synthesis of the solanidine alkaloids has been reviewed.20... 

The partial synthesis from solasodine of nitrogen-containing analogues of ecdysone has been explored.22 In the successful route, 7V,0-diacetylsolasodine (16b) was treated with TV-bromo acetamide and HCI04. The bromohydrin (26a) that was formed was reductively debrominated with chromous acetate and butanethiol to... 

Solaverbascine, occurring in S. verbasoifolium leaves, has been assigned structure (57) from spectral study and because it is formed by reductive ring-cleavage of solaso-dine (44) (G. Adam et al., Phytochem., 1980, 1, 1002) conversely it affords solasodine on manganese dioxide oxidation (Adam and H. T. Huong, Tetrahedron Letters, 1980, 21, 1931 J. prakt. Chem., 1981, 323, 839). The latter reaction occurs via 22-n double bond formation followed by spontaneous cyclization. 

Ozonolysis of solasodine (1) and of the derived enone (8), with oxidative work-up, gave the keto-acids (18) and (19), respectively. These products were characterized as their methyl esters and as the acetates of the products of lithium aluminium hydride reduction of the methyl esters. Ozonolyses of (20) and (21) to give analogous products were also described. The aglycone (22) of the steroidal glycoside osladine has been synthesized from solasodine via the azomethine (23) and ketone (24). ... 

Solacongestidine, as we have seen above, has been shown to be identical with the synthetic material (1). An alternative synthesis of this alkaloid from readily available solasodine (9) has been described. Sodium borohydride reduction of solasodine and acetylation gave the triacetate (10), which was converted in unexceptional steps, illustrated in Scheme 1, into (11). This base was then... 

Catalytic reduction (platinum oxide, acetic acid) of (25i )-22,26-epimino-3j3,16j8-diacetoxycholesta-5,22(A)-diene (CXXXI) and its 5 -6-dihydro derivative XCII and subsequent hydrolysis of the resulting saturated 0(3),0(16)-diacetate led almost exclusively to tetrahydro-solasodine A (CXLII) with (22(S)-configuration (265, 271) by the same sequence of reactions, the respective 5a,25(S-compound forms predominantly dihydrotomatidine B (CXLVII) together with smaller amounts of its (22(S )-stereoisomer CXLVI (272). 

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