Synthesis of enantiopure 1,2-azido and 1,2-amino alcohols regio- and stereoselective ring-opening of enantiopure epoxides by sodium azide in hot water.

A practical and convenient method for the efficient and regio- and stereoselective ring-opening of enantiopure monosubstituted epoxides by sodium azide under hydrolytic conditions is reported. The ring-opening of enantiopure styryl and pyridyl ()-epoxides by N in hot water takes place preferentially at the internal position with complete inversion of configuration to produce ()-2-azido ethanols with up to 99% enantio- and regioselectivity, while the ()-adamantyl oxirane provides mainly the ()-1-adamantyl-2-azido ethanol in excellent yield. In general, 1,2-amino ethanols were obtained in high yield and excellent enantiopurity by the reduction of the chiral 1,2-azido ethanols with PPh in water/THF, and then converted into the Boc or acetamide derivatives.

Asymmetric synthesis of nonracemic primary amines via spiroborate-catalyzed reduction of pure (E)- and (Z)-O-benzyloximes: applications toward the synthesis of calcimimetic agents.

Highly enantiopure (1-aryl)- and (1-naphthyl)-1-ethylamines were synthesized by the borane-mediated reduction of single-isomeric (E)- and (Z)-O-benzyloxime ethers using the stable spiroborate ester derived from (S)-diphenyl valinol and ethylene glycol as the chiral catalyst. Primary (R)-arylethylamines were prepared by the reduction of pure (Z)-ethanone oxime ethers in up to 99% ee using 15% of catalyst. Two convenient and facile approaches to the synthesis of new and known calcimimetic analogues employing enantiopure (1-naphthalen-1-yl)ethylamine as chiral precursor are described.

Synthesis and redox-enzyme modulation by amino-1,4-dihydro-benzo[d][1,2]dithiine derivatives.

A convenient method to prepare a series of benzodithiine derivatives was developed, via the synthesis of cyclic disulfide building blocks containing an amino-group linker. Some of the novel cyclic disulfide compounds are shown to modulate the activity of the redox-enzyme glutathione reductase.

Facile rearrangement of O-silylated oximes on reduction with boron trifluoride/borane.

[reaction: see text] Aromatic O-triisopropylsilyl ketoximes were efficiently rearranged to cyclic and acyclic aniline derivatives on reduction with BF3-ethearate/borane. The bulk of the substituents on the silicon atom, the size of the aliphatic ring, and the presence of alkoxy substituents on the aryl group all play an important role in the aniline.

Efficient synthesis of B-alkylated oxazaborolidines derived from ephedrine and norephedrine.

[reaction: see text] Representative B-butyl- and B-methyl-1,3,2-oxazaborolidines derived from ephedrine and norephedrine were prepared in good yield and excellent purity by one-pot treatment of B-H oxazaborolidines with the corresponding organolithium reagent and subsequent hydrolysis of the cyclic borohydride intermediate with anhydrous ammonium chloride.