Total synthesis of (.+-.)-ferruginol and (.+-.)-hinokione

Abstract

Stereospecific syntheses of (f )-ferruginol and (f)-hinokione were achieved in which the tricyclic ring system was assembled in the order C -BC -ABC. The key features of the approach involve: (1) the utilization of a lactone bridge as part of an enone protecting group in ring A; (2) the installation of an isopropyl group by the regioselective addition of lithium dimethylcuprate to a cross-conjugated dienone; (3) the elimination of the lactone bridge with concomitant aromatization of ring C; and (4) the reductive methylation of the enone in ring A to install the C-4 geminal dimethyl group and to guarantee the trans fusion of the AB rings.

Use of Conjugated Dienones in Cyclialkylations: Total Syntheses of Arucadiol, 1,2-Didehydromiltirone, (±)-Hinokione, (±)-Nimbidiol, Sageone, and Miltirone

“…Chart ) as the key synthetic intermediate (Scheme 12). Reductive alkylation, followed by removal of the C(3) carbonyl moiety using a thioketal/reduction sequence, completed the functionalization of the A ring (cf. 69 ).…”

“…Cyclialkylation of 79 to tricycle 80 occurred in high yield under mild conditions. Watt and co-workers have shown that compound 80 can be converted to hinokione in two steps …”

Aromatic abietane diterpenoids: total syntheses and synthetic studies

“…Hydrogenolysis of (±)-sugiol (62) over 30% Pd/C removed the benzylic ketone and produced (±)-ferruginol (3). 56 The resulting intermediate 296 was then elaborated to introduce the appropriate functionality in the C ring, previous protection of the enone moiety in the A ring. Thus, the ketalisation of compound 296 with ethylene glycol proceeded with concomitant lactonisation to give the bridged δ-lactone 297.…”

Novel Domino Reactions for Diterpene Synthesis

“…Similarly, the acid (11) was subjected to CH 3 SO 3 H-P 2 O 5 promoted domino acylation-cycloalkylation with veratrole (18) to yield the tricyclic ketone (19), which was * To whom the correspondence should be addressed. Fax: (91) (22) 26528547.…”

“…Acid 11 was then subjected to concentrated H 2 SO 4 promoted domino alkylation-cycloacylation with anisole (12) to yield the tricyclic ketone (22), which was subsequently transformed, as depicted in Scheme 6, to the octahydrophenanthrene (23), which has been previously converted [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33] to the antibacterial 16 diterpene, (()-totarol (4).…”