Ketones, fused ring bicyclic

Liu, D. Hong, S. W. Corey, E. J. Enantioselective Synthesis of Bridged- or Fused-Ring Bicyclic Ketones by a Catalytic Asymmetric Michael Addition Pathway. /. Am. Chem. Soc. 2006,128,8160-8161. 

With 0,-y-unsaturated a -diazo ketones, the resulting [2.1.0]-bicyclic systems (40) were quite unstable and underwent a [2 + 2] cycloreversion to generate ketenes (41), which were then trapped by nucleophiles (Scheme 7). The overall scheme has been named a vinylogous Wolff rearrangement and offers a novel entry to products usually derived from a Claisen rearrangement.102 A recent report describes its application for functionalized angular alkylation in fused ring systems.103 In contrast, the intramolecular re-... 

Enamines have been made from a bicyclic aldehyde (5)126 from bicyclic ketones (6)i27,i28, (7)129, (8)129 and (9)129, from cyclic ketones fused to a benzene ring, such as a-tetralone130-134 and jS-tetralone131,135,136, from ketones with a seven-membered ring133,137,138 fused to the benzene ring, or with a five-membered ketonic ring130,139-143 fused to the benzene ring. 

Stereoselective, fused-ring alicyclic alcohols are prepared in 10-77% yields from haloalkylalicyclic ketones. The cyclic ketones range from C5 to C7, with iodo-, bromopropyl-, or bromobutyl-substitution in the 2-position. Bicyclo[3.3.0]octan-l-ols, [4.3.0]nona-l-ols, [4.4.0]deca-l-ols, and [5.3.0]decan-l-ols are also prepared. When the side chain is extended to iodopentyl, no bicyclic products are obtained. Usually the ring fusion is cisoid [53],... 

The key step in the stereocontrolled total synthesis of the tricyclic (+)-kelsoene by M. Koreeda et al. was a base-catalyzed homo-Favorskii rearrangement of a y-keto tosylate to elaborate the 4-5 fused ring portion of the target molecule. The bicyclic 5-6 fused y-keto tosylate was treated with excess potassium fert-butoxide, which effected the desired rearrangement in less than 2 minutes at room temperature. The nucleophilic solvent was too bulky to effect the opening of the cyclobutanone intermediates, making their isolation possible. The mixture of isomeric cyclobutanones was converted to a separable 1 1 mixture of cyclobutanones with p-TsOH, and the ketone functionality was then removed via the corresponding tosylhydrazone. 

Fused 2,3,4,6-tetrasubstituted pyridines 7, 9 and 10 can be prepared by two complimentary procedures from fused bicyclic ketones. In the first synthetic approach it is the a,P-unsaturated ketone 6 that is part of the fused ring system. 

Monoterpenoid ketones are cyclic compounds in which a carbonyl group is bonded to two carbon atoms. They are produced by oxidation of alcohols and are relatively stable molecules. Monocyclic ketones such as pulegone contain a single carbon ring while bicyclic ketones like camphor contain two fused rings. Most ketones have the suffix one . 

A possible mechanism that features a six-membered transition state is given in Scheme 18 (38, 43). The high catalytic activity stems from the excess strain of the B=N bond in the 5/5-fused bicyclic ring system, which results in strong coordination of the angular nitrogen atom to BH3 to form the active dinuclear species. The rate and stereoselectivities of the reaction of trihalomethyl ketones has been explained on the basis of the X-ray analysis of the substrates. 

With metallic lithium, the problem of alkyllithium addition to the electrophile is avoided, and provided the reacting substituents were arranged cis on the existing five-membered ring, the ketone 94 could be cyclised to a single isomer of the bicyclic 5,5-system 95 in 95% yield.54 The mms-fused system 97 formed in only 44% yield from 96, as a mixture of diastereoisomers - the major product was then simple reduction to the uncyclised alkene 98. 

Lactam formation from an oxidative cleavage of the bicyclic zero bridge is well known, for example, VIII/197 — VIII/200 [115]. Because of the relative positions of a ketone and a secondary lactam in the ten-membered ring compound, VIII/199, however the only stable structure is that of the fused five/seven ring system in VIII/200 [116]. The substituted 3(2H)-pyrazolones VIII/201 are opened oxidatively by periodate to VIII/202 [117]. 

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