Butenandt’s ketone

The final stage, the cyclization of acid (5) to form Butenandt s ketone (6), is carried out either via the acid chloride under the action of stannic chloride [137, 144] or from the acid as such by the action of hydrofluoric acid (yield 85%) [140] or 90% sulfuric acid (yield 87%) [143]. The synthesis of analogs of the ketone (6) containing no 3-methoxy group has also been described [145, 146]. 

The first total synthesis from Butenandt s ketone (6) was achieved by Bachmann et al. in 1939 [137, 147], who obtained racemic equilenin (23) (Scheme 2). The introduction of the atom into the ketone (6) was carried out by oxalylation, that of the 0 3 atom by angular methylation, and that of the and atoms by the Reformatskii reaction. The closure of ring D was effected by Dieckmann cyclization. 

The second route to the total synthesis of equilenin from Butenandt s ketone (6) was developed in 1945 by Johnson et al. [163-169]. In this, the Ci7 atom was introduced by formy lation and the 0 3 atom by angular methyl-ation, while the introduction of the 0 5 and C10 atoms and cyclization with the formation of ring D were carried out in a single stage by Stobbe condensation (Scheme 4). 

Several total syntheses of steroid compounds and their analogs have been carried out via the 13-methyl derivative of Butenandt s ketone (53). 

---

See also in sourсe #XX -- [ , , ]

---