Synthesis and photoreactions of 3-oxa-tricyclo[5.2.2.01,5]undecenones: a novel, stereoselective route to oxa-triquinanes and oxa-sterpuranes

The synthesis of 11-methyl-3-oxa-tricyclo[5.2.2.01,5]undecenones and their photochemical reactions upon triplet (3T) and singlet (1S) excitation is described. Oxidation of hydroxymethylphenol gave a ketoepoxide by intramolecular cycloaddition. Manipulation of the oxirane ring furnished the chromophoric systems. Triplet excitation of these gave tetracyclic compounds containing an oxatriquinane framework. Singlet excitation furnished the tricyclic compound having an oxasterpurane ring system in a stereoselective fashion.© Elsevie

Cycloaddition between electron deficient partners: an efficient regio- and stereoselective synthesis of functionalised bicyclo[2.2.2]octenones. A tandem alkylation, stereochemical inversion and aldol condensation

A novel one step regio- and stereoselective synthesis of functionalised bicyclo[2.2.2]octenones from readily available aromatic precursors is described. The methodology involved in situ generation of reactive spiroepoxycyclohexadienones and π4s+π2s cycloaddition with methyl vinyl ketone. Study on π-facial alkylation that led to the formation of homobrendane derivatives as a result of stereochemical inversion and aldol condensation in tandem, is also presented. The crystal structure of 6-acetyl-1-methoxy-bicyclo[2.2.2]oct-7-en-2-one-spiro[3,2′]oxirane and 3-methoxy-4,6,9-trimethyltricyclo[4.3.1.03,7]decan-8-en-5-one-spiro[2,2′]oxirane is also reported.© Elsevie

Cycloaddition of cyclohexa-2,4-dienones, ring-closing metathesis, and photochemical reactions: A common stereoselective approach to duprezianane, polyquinane and sterpurane frameworks

A novel approach to three different types of carbocyclic frameworks belonging to dupreziananes, sterpuranes, and polyquinanes from simple aromatic precursors has been presented. Cycloaddition of appropriately appended cyclohexa-2,4-dienones with acyclic dienes gave bridged bicyclic octanes suitably disposed with olefinic chains, which upon ring-closing metathesis led to functionalized tricyclo[5.2.2.0(1,5)]undecanes related to dupreziananes. Photochemical sigmatropic 1,2- and 1,3-acyl shifts in tricyclo[5.2.2.0(1,5)] undecanes upon triplet and singlet excitation provided stereoselective routes to sterpurane and polyquinane frameworks