SE373848

• Main Authors: RADSCHEIT K, STACHE U, HAEDE W, FRITSCH W
• Format: Patent
• Language: English
• Published: 17.02.1975
• Subjects: CHEMISTRY; HETEROCYCLIC COMPOUNDS; METALLURGY; ORGANIC CHEMISTRY; STEROIDS

1362383 Cardenolides; bufadienolides FARBWERKE HOECHST AG 7 July 1971 [7 July 1970] 31974/71 Heading C2U [Also in Division A5] The invention comprises (A) the compounds 3#,14 - dihydroxy - 5α,14# - bufa - 20,22 - dienolide (Ia); 3#-hydroxy-5α,14α-card-20(22)- enolide; 3# - hydroxy - 5α - bufa - 14,20,22- trienolide; and 3#-hydroxy-5α,14α-bufa-20,22- dienolide; and (B) a process for preparing compounds of formula (wherein R 1 is the lactone ring of a 20(22)- cardenolide or 20,22-bufadienolide; R 2 is CH 3 , CH 2 OH or CH 2 OCOCH 3 ; R 3 is H, OH or acyloxy; R 4 is H; or R 3 + R 4 is epoxy or an extra C-C bond; and R 5 and R 6 are each H, OH or acyloxy) which comprises reducing the corresponding 3-oxo-#4 compounds (wherein R 2 is alternatively CHO and R 5 and R 6 are each alternatively oxo) with a reducing agent which is more powerful than NaBH 4 , in the presence of an organic nitrogen base at - 30‹ to + 60‹ C. Any oxo groups at positions 11, 12 and 19 are reduced concomitantly. Specified reducing agents are the borohydrides of Li, Mg, Ca, Sr, Ba, Zn and Al, the trimethoxy borohydrides of Na and Li, the aluminium hydrides of Na, Li and Mg, aluminium hydride, lithium trimethoxy aluminium hydride, diborane, pyridine-borane, ethane-1,2- diamine-borane and (3-methyl-2-butyl)borane. Compound Ia supra is alternatively prepared from 3# - hydroxy - 5α - bufa - 14,20,22 - trienolide (III) by the sequence : III # III 3- formate # 15α-bromo-(Ia)-3-formate # Ia 3-formate -# Ia. 3 - Oxo - 14α - bufa - 4,20,22 - trienolide is prepared from the corresponding #5-3#-ol by Oppenauer oxidation. Compounds I are said to be cardiotonic, and may be made up with carriers into pharmaceutical compositions for oral and parenteral administration.