Efficient synthesis of (1S,5S)-4-alkyl-6,6-dimethylbicyclo[3.1.1]hept-3-en-2-ones from (1R,5S)-(+)-nopinone and preparation of some chiral building blocks suitable for the asymmetric synthesis

Biotransformation of (S)-cis-verbenol with Nocardia corallina B-276

“…19 [α] 20 D = -126.5° (c 0.29, CHCl 3 )]; IR(neat): ν max /cm -1 1679; NMR (400 MHz, CDCl 3 ): δ 5.73 (1H, m), 2.79 (1H, m); 2.64 (1H, dt, J 5.7, 1.8 Hz), 2.41 (1H, t, J 5.1 Hz), 2.08 (1H, d, J 9.0 Hz), 2.01 (3H, s); 1.49 (3H, s); 1.01 (3H, s): 13 C NMR (100 MHz, CDCl 3 ): δ 203.6, 169.9, 120.9, 57.4, 53.9, 49.5, 40.7. 26.5, 23.5, 21.9 ppm;and thin layer chromatography against an authentic sample, the data were in full accordance with the literature values 19,20.…”

Navigating the Chiral Pool in the Total Synthesis of Complex Terpene Natural Products

“…101 This material could be directly converted to ketal 73 (ethylene glycol, acid) allowing for a subsequent allylic oxidation leading to enal 74 . Conversion of 74 to its tosylhydrazone proceeded cleanly, setting the stage for one of several key steps in the synthesis.…”

Monoterpenoids

“…524 The mechanism of the acid-catalysed ringopening of a-pinene epoxide 361 does not involve participation ent-346 reacts with cycloheptatriene in the presence of catalytic amounts of its own molybdenumcarbonyl complex 368 to give the adduct 369 which was obtained as a single diastereoisomer whose structure was assigned by X-ray analysis.530 (+)-Nopinone 370 has been converted into the tertiary allylic alcohols 371 which suffer oxidative rearrangement to yield ( -)-verbenone 339 and its derivatives 372. 531 Nopyl toluene-p-sulfonate 378 has previously been reported to give the cyclobutanol 379 on acetolysis, but a second look at this transformation has revealed that the correct structure for the solvolysis product is, in fact, 380.535 This tertiary alcohol, which has been named fortesol, can be prepared on a large scale, is very resistant to rearrangement under strongly acidic conditions, and has found applications in the optical resolution of carboxylic and phosphinic acids. The synthesis of (+)-apopinene 381 via the decarbonylation of (+)-myrtenal 382 has been reviewed.…”