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Research has been conducted on (R)-salbutamol. The results of enantioselective synthesis of this compound carried out via the use of chiral C (sub)2 symmetric acyl anion equivalent are presented.

Research has been conducted on N-sulfonyl imines derived from aromatic, aliphatic, heteroaromatic and unsaturated aldehydes. The imines have been treated with trimethylsilyldiazomethane to produce C-silylaziridines and the synthetic potential of these C-silylaziridines has been investigated.

Research has been conducted on the Baylis-Hillman reaction between cyclohexenone and benzaldehyde. Results indicate the acceleration of this reaction when it is conducted in water and the origin of this acceleration rate is discussed.

A study was conducted to examine asymmetric oxidation of a series of 1,3-dithianes. Asymmetric induction was determined in the formation of the monoxide with all esters while the racemic oxidation of 2-carbethox-1,3-ithiane and a range of oxidants were also evaluated in the study. Results indicated that the oxidation of ethyl 1,3-dithiane-2-carboxylate can be effectively determined by the Modena oxidation protocol.

A study was conducted to analyze the catalysis of the Baylis-Hillman reaction associated with the coupling of an unsaturated carbonyl compound/nitrile with aldehydes. Reactions were carried out utilizing tert-butyl acrylate and benzaldehyde with various Lewis acids. Results indicated that the use of catalytic amounts of oxygen-rich donor ligands supported an increase in reaction rate.

Research was conducted to examine the 1,3-dipolar cycloaddition reactions of trans-2-methylene-1,3-dithiolane 1,3-dioxide with nitrones. The existence of a C2 symmetry element in (1R,3R)-2-methylene-1,3-dithiolane 1,3-dioxide to a diene are symmetry related and, thus, identical, which reduces the number of competing transition states in the reaction. (1R,3R)-2-methylene-1,3-dithiolane 1,3-dioxide revealed very high reactivity and stereoselectivity in Diels-Alder reactions with a range of dienes.

The synthesis of C-4-substituted 2-oxabicyclo[3.3.0]oct-7-en-ones and their reactivity in palladium-mediated substitution reactions was reported. Reaction rates were found directly related with increasing electron-withdrawing ability of the substituent(X). A strong correlation between rate and pKa of the corresponding substituted acetic acids(XCH2CO2H), with the exception of X=OH was also observed.

The reactions of metalated trans-1,3-dithiolane 1,3-dioxide with aldehydes were investigated. The results showed that the anion of the compound is sufficiently stable and reacted with different aldehydes to form secondary alcohols with moderate to high selectivity. The use of 2.4 equiv of lithium hexamethyldisilazide at -78 degrees C, resulted in higher diastereoselectivity.

A short, asymmetric method for the synthesis of carbocylic analogues of nikkomycins and polyoxins is described. The scheme involves the palladium-catalyzed substitution reaction of an unsaturated lactone as the key step. The reaction conditions for the stereospecific total synthesis of the carboxylic analogue of uracil polyoxin C are presented.

A study of the anion chemistry of 1,3-dithiane 1,3-dioxide with aldehydes and ketones shows that it undergoes selective addition reactions with aromatic aldehydes under equilibrium-controlled conditions. Li, Mg, Al, Ce and Ti exhibit reduced selectivity but Zn4 provided improved selectivity with aromatic aldehydes. The model developed to explain the disteroselectivity of aldehydes includes complexation of metal alkoxides with axial sulfoxide.

A novel method is presented which would facilitate in the preparation of 2,3-methanoamino acids through the combination of dehydroamino acid with tosylhydrazone salts. The thermal 1,3-dipolar cycloaddition is termed as an excellent method for cyclopropane amino acids.

Research has been conducted on pyrazoles. The authors describe the preparation of these pyrazoles via 1,3-dipolar cycloadditions of diazo compounds.

Research has been conducted on ketene dithioacetals. The authors report that these compounds undergo Sharpless-type asymmetric oxidation via the use of such compounds as cumene hydroperoxide in order to produce trans bis-sulfoxides with complete control of diastereoselectivity and enantioselectivity.

Research has been conducted on quinuclidine-based catalysts. The reactivity of these catalysts in Baylis-Hillman reaction has been investigated, and the correlation between base's reactivity and basicity has been established and described.

The discovery that the reaction between chloroform and carbonyl compounds can be promoted under milder conditions, in high yields, using less basic catalysts such as cyclic amidines is discussed. It is observed that amidines and guanidines are extremely active promoters of the reaction between chloroform and benzaldehyde.

A study was conducted to prepare enantiomerically and diastereomerically pure spirocyclic bis-sulfinyl oxiranes in four stages. Sodium hydroperoxide and lithium tert-butyl peroxide were utilized in the epoxidation of the bis-sulfoxides while the stereochemistry of the stereocenter was determined with bidentate nucleophile (1R,2R)-1,2-diaminocyclohexane. Results indicated that the oxiranes supported chiral substrates used for various alpha-heterosubstituted carbonyl compounds.

Research was conducted to examine the reaction of zinc carbenoids derived from Et2Zn and ClCH2I with sulfides. An aldehyde was treated with Et2Zn, ClCH2I and tetrahydrothiophene which generated unsaturated aldehydes without undergoing cyclopropanation. Results suggest that reaction of the zinc carbenoid with the sulfide was exceedingly faster than reaction with the alkene. Thus, a novel application of organozinc reagents toward the epoxidation of carbonyl compounds via the intermediacy of sulful ylides was developed.

A new catalytic and asymmetric synthetic route to aziridines is introduced. The process, which affords highly enantioselective aziridines in high yields, requires the slow addition of a diazo compound to an imine in the presence of a catalytic amount of metal salts and enantiomerically pure sulfides in a neutral environment. It is applicable to a variety of imines such as N-tosylimines and N-(diphenylphosphinyl)benzaldimines as well as diazo compounds such as N,N-diethyldiazoacetamide and ethyl diazoacetate.

The newly developed chiral ketene equivalent shows the highest levels of selectivity for a wide range of dienes and can be obtained in four steps. Ketene equivalents are mainly used as partners in Diels-Alder reactions in the preparations of cyclic, fused and bridged ketones. The diastereocontrol activity of the ketene equivalents obtained from vinyl sulfoxides are low and they are poor dienophiles. Vinyl sulfoxide shows good stereoselectivity under Lewis acid catalysis and act as ketene equivalent with cyclopentadiene.

Chiral, bisfunctionalization of precursor molecules is an effective technique in the synthesis of compounds symmetric with reference to carbon 2 with high enantiomeric excess. The process requires the external addition of two asymmetric centers and allow the asymmetric reactions to occur at the same time. It is necessary to to have fine reagent control to promote the generation of products which are optically active. Further studies reveal that the Modena oxidation method is better than the Kagan protocol in the preparation of a dithiane dioxide utilizing chiral, bisfunctionalized precursor molecules.

The reactivity of a variety of f-based catalysts in the Baylis-Hillman reaction has been examined, and a straightforward correlation between the basicity of the base and reactivity has been established, without exception. The following order of reactivity was established with pK[sub a]'s of the conjugate acids (measured in water) given in parentheses: quinuclidine (11.3), 3-hydroxyquinuclidine (9.9), DABCO (8.7), 3-acetoxyquinuclidine (9.3), 3-chloroquinuclidine (8.9), and quinuclidinone (7.2). The higher than expected reactivity of DABCO, based on its pK[sub a], was analyzed by comparing the relative basicity of DABCO and 3-acetoxyquinuclidine in DMSO. It was found that in aprotic solvent, DABCO was 0.6 pK[sub a] units more basic than 3-acetoxyquinuclidine, thus establishing a direct link between pK[sub a] of the amine and its reactivity. In contrast to previous literature work that reported the contrary, quinuclidine, which has the highest pK[sub a], was found to be the most active catalyst. The reaction profile with quinuclidine showed significant autocatalysis, which suggested that the presence of proton donors might further enhance rates. Thus, a series of additives bearing polar X-H bonds were investigated and it was found that methanol, triethanolamine, formamide, and water all provided additional acceleration. Methanol was found to be optimum, and the powerful combination of quinuclidine with methanol was tested with a host of aldehydes and Michael acceptors. Not only were the reactions more efficient and faster than previously reported, but now new substrates that were previously unreactive could be employed. Notable examples include the use of acetylenic aldehydes and the employment of vinyl sulfones, acrylamides, δ-1actones, and even α,β-unsaturated esters bearing a β-substituent. [ABSTRACT FROM AUTHOR]