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Pyrazolo[5,1-c][1,4]benzoxazines were prepared by the reaction of 2-(allyloxy)phenylhydrazine with arylaldehydes in the presence of hydrochloric acid. The formation of the fused heterocycles can be explained by intramolecular 1,3-dipolar cycloaddition reaction of cationic dipole, i.e‥, hydrazonium chlorides.

2-(Trimethylsilyl)ethyl benzenesulfenate was allowed to react with several halides in the presence of tetrabutylammonium fluoride (TBAF) to afford the corresponding phenyl sulfoxides as the main product. In the reaction of 2-(trimethylsilyl)ethyl benzeneselenenate and several halides with TBAF, the corresponding alcohols were obtained as the main product.

O-Ethoxycarbonyl hydroximoyl chloride serves as a stable precursor for nitrile oxide and is converted into the 1,3-dipole when heated under reflux in pyridine.

By the catalysis of lipases, racemic 1-phenylethanol 1a is reacted with diketene in isopropyl ether at room temperature to give (S)- 1a (R1=Me, R2=Ph, 36%, 99%ee) and (R)-1-phenylethyl acetoacetate 2a (51%, 77%ee). The strategy was also successfully applied to recemic 1-(1-naphthyl)ethanol 1b, 1-(2-naphthyl)ethanol 1c, 1-phenyl-2-propanol 1d, 1,2,3,4-tetrahydro-1-naphthol 1 e, and 2-octanol 1 f with high E-values up to >100.

Optically active (R,S)- and (S,R)-tricarbonyl {2-[1-(N,N-dimethylamino)ethyl]benzenethiol}chromiums have been prepared in moderate yield by the regioselective lithiation of tricarbonyl [N,N-dimethyl-α(R)-phenylethylamine]chromium and subsequent reaction of the product with elemental sulfur. The structure of the (R,S)-benzenethiolchromium complex was fully characterized by X-ray crystallography. The chiral benzenethiolchromium complexes reacted with cyclopentene oxide, cyclohexene oxide, 1-methylcyclohexene oxide, cycloheptene oxide and cyclooctene oxide and, after oxidative removal of the chromium moiety, gave the corresponding trans β-hydroxyalkyl aryl sulfides in high yield with moderate diastereoselectivity. The reaction proceeded without additives and the diastereoselectivity was not affected by the addition of lanthanide(III) complexes which are known to promote the ring-opening of an epoxide with benzenethiol.

Kinetic resolution of (±)-4-substituted [(±)-1], 3-substituted [(±)-4] and 3,4-disubstituted oxetan-2-ones [(±)-7] was effected by the action of lipases in organic solvents. The substrates (±)-1, (±)-4 and (±)-7 were prepared by [2 + 2] cycloaddition of aldehydes with ketene, intramolecular substitution of 3-bromoalkanoic acids and the Adams cyclization of anti- and syn-3-hydroxyalkanoic acids, respectively. Lipase PS exhibited good activity towards all the oxetanones and was employed for the resolution experiments except with (±)-4-methyloxetan-2-one (±)-1a for which PPL was used. The stereoselectivity was satisfactory for obtaining oxetan-2-ones of high ee’s except for a few cases. The configuration of new compounds was established by chemical correlation and CD spectroscopy.