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Solanum alkaloids, 121. Partial Synthesis of the Steroid Alkaloids Teinemine, 22‐Isoteinemine, Etioline, and 25‐Isoetioline
Author(s) -
Quyen Le Thi,
Ripperger Helmut,
Schreiber Klaus
Publication year - 1991
Publication title -
liebigs annalen der chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 0170-2041
DOI - 10.1002/jlac.199119910126
Subject(s) - solasodine , chemistry , diol , stereochemistry , steroid , derivative (finance) , alkaloid , sodium , solanum , organic chemistry , botany , biochemistry , biology , hormone , financial economics , economics
The rare 16α‐hydroxylated steroid alkaloids teinemine [(22S,25S)‐22,26‐epiminocholest‐5‐ene‐3β,16α‐diol, 8 ], 22‐isoteinemine [(22R,25S)‐22,26‐epiminocholest‐5‐ene‐3β,16α‐diol, 10 ], etioline [(25S)‐22,26‐epiminocholesta‐5,22(N)‐diene‐3β,16α‐diol, 12 ], and 25‐isoetioline [(25R)‐22,26‐epiminocholesta‐5,22(N)‐diene‐3β,16α‐diol, 21 ] are synthesized from the abundant spirosolane alkaloids tomatid‐5‐en‐3β‐ol [(25S)‐22βN‐spirosol‐5‐en‐3β‐ol, 1 ] and solasodine [(25R)‐22αN‐spirosol‐5‐en‐3β‐ol, 15 ], respectively. The crucial stages of these syntheses are the conversions of 1 or 15 into the N‐protected (22S,25S)‐, (22R,25S)‐, and (22S,25R)‐22,26‐epimino‐3β‐hydroxycholest‐5‐en‐16‐ones 6, 7 , and 18 as well as their reductions with sodium/ 2‐propanol to the 16α‐hydroxy compounds teinemine ( 8 ), 22‐isoteinemine ( 10 ), and (22S,25R)‐22,26‐epiminocholest‐5‐ene‐3β,16α‐diol ( 19 ), respectively. By treatment with sodium methanolate the N‐chloro derivatives 9 and 11 of 8 and 10 afford etioline ( 12 ). In an analogous manner, the N‐chloro derivative 20 of 19 is converted into 25‐isoetioline ( 21 ).