Bicyclo heptanone synthesis

Irradiation of the ketone (6) in argon-degassed cyclohexane brings about Norrish Type I fission. In this case decarbonylation does not result and the triplet biradical formed by the fission affords the aldehyde (7). The enol (8) is also a product of this irradiation. An aldehyde is also the principal product on irradiation of (9) in benzene. The a-fission affords the aldehyde derivative (10) in 90% yield. Analogous behaviour is observed on irradiation of bicyclo-heptanone (11) to afford an aldehyde that was a key intermediate in the synthesis of dimethyl secologanoside. ... 

The synthesis of the bicyclo heptanone synthon 21 was achieved in five steps from isovaleraldehyde. The silyloxy aldehyde synthon 22 was synthesized from the readily available isobutenol. The cycloaddition was first attempted using standard Lewis acid conditions, with either tin chloride or tin triflate however, this led to competitive elimination and the cyclic adduct was not obtained. It was later discovered that the use of the hindered catalyst MADNTfa [(ArOjaAlNTfa] resulted in the cycloaddition, afrbrding... 

The application of this reaction to other ring systems has shown that the yield of the bicyclic hydrocarbon decreases as the strain involved in the product increases. For example, the mercury sensitized decomposition of bicyclo [3.2.0] heptanone-3 (XXIII) leads to very little of bicyclo [2.2.0] hexane and gives more of bicyclo [2.1.1] hexane than of bicyclo [2.2.0] hexane. The reaction has been successfully applied to the synthesis of a substituted bicyclo [2.1.0] pentane (XXVIII) from a sub-... 

A stereoselective synthesis of 3-( 1,2,4-triazolo[4,3-A ]azin-3-yl)-bicyclo[2.2.1 ]heptanones 58 starting from (l/ )-(+)camphor 56 has been described. The reaction comprises oxidative cyclization of the intermediate hydrazones 57 with methanolic bromine <02TA821>. 

A general Claisen rearrangement leading to the starting dienes (1) is included in an example of this reaction for synthesis of 3,3-dimethyl-ci>2-bicyclo-[3.2.0]heptanone (5). 

Stork and Ficini10 found that intramolecular cyclization of a-diazoketones furnishes interesting possibilities for synthesis thus (1) was cyclized in good yield to bicyclo-[4.1.0]heptanone-2 (2) in good yield ... 

MacDougall, J.M., Turnbull, P., Verma, S.K., and Moore, H.W. (1997) Synthesis of highly substituted bicyclo[3.2.0]heptanones from 3-homoallylcyclobutenones atotal synthesis of ( )-precapnelladiene. /. Org. Chem., 62, 3792-3793. 

Chiral bicyclo[3.2.0]heptanone has been recognized as a chiral precursor for (+)-prostaglandin A2 136 and (+)-prostaglandin-F2a 137 synthesis. The reduction of racemic bicyclo[3.2.0]hept-2-en-6-one 139 in high optical purity by cells of Mortierella ramanni-ana has been demonstrated (Fig. 49). The same organism has also been used for the stereoselective reduction of 7,7-dimethylbicyclo[3.2.0]hept-2-ene-6-one 139 to prepare the chiml synthon for (+)-leukotiiene B4 synthesis [247]. 

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