.alpha.-Halo ketones. 10. Regiospecific homologation of unsymmetrical ketones

Synthesis and chemistry of homocubanes, bishomocubanes, and trishomocubanes

“…No convincing arguments have been forwarded to account for the unusual regioselectivity of each of the semibenzilic acid rearrangements 23 -24, 26 -27, and/or 29 -30 cited in Schemes 2-4. Substituted homocubanes also have been prepared by reaction of transition-metal complexes with cubane SCHEME 6 37 (major dPh p r o d u c t ) 3 8 @[$ (minor F I Q d u C t l SCHEME 7 40 : n n r i n o u t a n e ' (see section 1.B). Thus, reaction of cubane (33) with a stoichiometric amount of [Rh(CO),Cl], affords homocubanone (34).…”

Baeyer–Villiger Oxidation of the Bicyclo[2.2.2]octanone System Revisited: Searching for a Modular Construction of Heavily Substituted Cyclohexanes Based on m‐CPBA Mediated Selective Oxygen Insertion

“…Furthermore, as syn or anti ‐C8 substituents in bicyclo octanones could dictate the migration of the methylene unit in preference to the bridgehead carbon, we planned to use a bulky protecting group at C2 and oxo‐substitution at C8 to divert the reaction course in a more elaborate fashion. The directing effect of the substituent α to the carbonyl group was first targeted in an attempt to see whether the Baeyer–Villiger reaction of an α‐bromo ketone9 would permit regiospecific ring opening. To this end, conversion of bicyclic aldol 2a to its α‐halogenated derivative 2c was accomplished by a three‐step sequence in 90 % overall yield.…”

Synthesis of (R)-2-(Benzyloxy)-tetrahydro-5,5-dimethylfuran by a New Oxidative Rearrangement

“…This lactol will be in equilibrium with the corresponding ketone 11, which can undergo another Baeyer-Villiger oxidation to give the acetate 12. This second oxidation is favoured by the presence of an oxygenated function in the α-position [12]. The rearrangement to the lactol 6 maintaining the chirality could be understood through the intermediacy of a hemiorthoester 13, which is the compound that finally rearranges to afford lactol 6.…”