A stereocontrolled synthesis of norphenyl hyperolactone C together with its utility as a direct precursor to the anti-HIV agent hyperolactone C and analogues by addition of organolithiums, are described. Preliminary studies to access this key building block in a catalytic enantioselective manner are also reported.

The Wittig reaction and its variants are the most powerful approaches for constructing carbon-carbon double bonds in organic synthesis due to their unambiguous positioning and good stereoselectivity.1 Of the recent developments,2-4 much attention has been paid to ylide olefination of aldehydes3 and ketones4 under neutral conditions by transition metal complex-catalyzed decomposition of diazo co...

the reaction between ni(ii), co(ii), cr(iii) bitrates, ni(ii) chloride and ambidentate a-keto ylide benzoylmethylenetriphenylphosphine (bppy) resulted in isolation of [ni(bppy)2](no3)2.2h2o, [ni(bppy)2]cl2, [co(bppy)2](no3)2 and [cr(bppy)3](no3)3; 2h2o. the compounds were characterized by elemental analyses and infrared 1hnmr spectroscopy, molar conductivity in solution and molecular weight mea...

The reaction of dimethyl acetylenedicarboxylate (DMAD) with C(60) in the presence of hexamethylphosphorous triamide (HMPT) or hexaethylphosphorus triamide (HEPT) results in fullerene derivatives incorporating HMPT or HEPT ylides. The ylide derivatives exhibit unusual electronic absorptions in the visible region (435-660 nm), likely due to the presence of the ylide moiety. Electrochemical studie...

Acyclic diazodicarbonyl compounds react at room temperature with cycloaliphatic thioketones, e.g. 2,2,4,4-tetramethyl-3-thioxocyclobutanе-1-one and adamantanethione, via a cascade process in which the key step is a 1,5-electrocyclization of the intermediate thiocarbonyl ylide leading to tetrasubstituted spirocyclic 1,3-oxathioles. The most reactive diazodicarbonyl compound was diazoacetylaceton...

The reaction of a sulfur ylide with a chiral non-racemic sulfinyl imine afforded the desired aziridine in excellent yield and subsequent oxidation of the sulfinyl moiety dissolved in anhydrous dichloro-methane using a 75% aqueous solution of 3-chloro-per-oxy-benzoic acid afforded the title compound, C(14)H(27)NO(6)S. The configuration of the newly formed stereogenic center at the point of attac...

A new method for enantioselective organocatalytic cyclopropanation is described. This study outlines the identification of a new class of iminium catalyst based on the concept of directed electrostatic activation (DEA). This novel organocatalytic mechanism exploits dual activation of ylide and enal substrates through a proposed electrostatic activation and stereodirected protocol. Formation of ...

A chiral Lewis acid-promoted enantioselective cyclopropanation using phenyliodonium ylide as the carbene precursor was developed. A variety of spirocyclopropane-oxindoles with contiguous tertiary and all carbon quaternary centers were obtained in excellent outcomes (up to 99% yield, >19 : 1 d.r., up to 99% ee). EPR spectroscopy study supported a stepwise biradical mechanism.