Oxetanes, dioxetanes, oxetanediones and 2-oxetanones p-lactones

A new stereocontrolled synthetic route to the potent proteasome inhibitor omuralide 46 has been developed from methyl pyroglutamate 07JOC10108 . The development of a new convertible isocyanide, indole-isocyanide, for ready access to pyroglutamic acids has culminated in the formal total synthesis of omuralide featuring a stereocontrolled Ugi reaction 07OL3631 . A novel enantioselective total synthesis of 20S proteasome inhibitor salinosporamide A 47 included, as a key feature, an intramolecular aldol cyclization 07OL2289 . A concise total synthesis of ( )-salinosporamide A, ( )-cinnabaramide A, and derivatives via a bis-cyclization process has been documented 07OL2143 . The 

Key i) NaOCl, CeCl3-7H20, CH2C12, RT. ii) (a) NaN3, DMSO (b) Pd/C, H2, MeOH. 

Phosphacyclobutene P-oxides 64 are produced by the reaction of titanacyclobutenes with dichlorophenylphosphine 07CEJ4077 . The large instability of heterophosphete compounds 65, composed of a four-membered unsaturated ring with a pentavalent phosphorus atom and a heteroatom, has been identified and characterised by first-principle molecular orbital computations, at several levels of theory showing that strong electron- 

Pierce, S. Aldridge, C. Jones, T. Gans-Eichler, A. Stasch, N.D. Coombs, D.J. Willock, Angew. Chem. Int. Ed. 2007, 46, 2043. 

Rodriguez, D. Scheschkewitz, H. Gomitzka, D. Bourissou, G. Bertrand, 

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