(1) The use of nitrosoalkenes, vinylnitrosonium cations, and nitroalkenes in heterodiene (4+2); cycloadditions. (2) Experimental, spectroscopic, and theoretical investigations of phosphorus (V) stabilized allyl anions

1. (4+2) -Cycloadditions of nitrosoalkenes, vinylnitrosonium cations, and nitroalkenes are discussed.;;Both intra- and intermolecular cycloadditions of nitroalkenes with unactivated olefins under Lewis-acid catalysis were investigated. Tin tetrachloride was the Lewis acid of choice. VT-NMR studies were done on the nitroalkene/tin tetrachloride complex. The equilibrium thermodynamic parameters for complexation were determined in two solvents. The complex was 1:1 in stoichiometry. The intramolecular cycloadditions were found to be stereospecific with both (E)-and (Z)-trisubstituted nitroalkenes. Intermolecular cycloadditions were found to proceed efficiently and stereoselectively with 1-nitrocyclohexene. Elaboration of the cycloadducts was investigated, including their use as 1,3-dipoles in (3+2) -cycloadditions, and their cleavage to afford hydroxy ketones or derivatives thereof.;2. Anions derived from allyl phosphonic diamides were examined for their ;The silyloxime of an ;NMR indicated phosphorus-(V)-stabilized, allyl anions in ethereal and hydrocarbon solvents to be mixtures of probably monomeric (E)- and (Z)-isomers with the (E)-isomer predominating. The carbon bearing phosphorus was shown to undergo substantial sp;Large-basis-set, well-correlated, ab initio calculations were performed on phosphine oxide and phosphinous acid. The difference in equilibrium stabilities was 2.8 kcal/mole and the barrier to unimolecular rearrangement was 68 kcal/mole. Allyl phosphonic diamide was studied at the 3-21G(*) level as a neutral, free-anionic, and lithiated species. The free anion was found to exist in both (E)- and (Z)-forms with a planar allylic...