An efficient diastereoselective route to differentially protected anti-4-amino-1-alken-3-ols

Zinc-promoted hydroxyallylation of alpha-amidoalkyl arylsulfones 4 using 3-bromo-propenyl methyl carbonate 5 proceeds smoothly in DMF at room temperature to afford high yields of differentially protected anti-1,2-amino alcohols 6.     

Synthesis of anti-2-aryl-4-en-1-ols from the corresponding syn isomers

Russian Journal of Organic Chemistry - Stereoselective synthesis of anti-2-aryl-4-en-1-ols from the corresponding syn isomers was accomplished with 71–83% yields via the Mitsunobu reaction.     

Synthesis and Photochemistry of syn- and anti-9,10-Epoxy-1, 4-dihydro-1,4-ethanonaphthalene-2,3-diones

The title epoxydiketones were prepared stereoselectively, direct epoxidation of 3a-c with MCPBA produced syn isomers la-c whereas epoxidation of 4a-d followed by saponification of the spirolactone rings gave anti isomers 2a-c. The stereochemistry of 1a and 2a was established by X-ray diffraction, whereas that of the remaining epoxydiketones was determined from the correlation of visible, ¹H, and ¹³C NMR spectral data; the differences between spectra of the corresponding syn and anti isomers are explained in terms of through-space interaction and steric effects. Photolysis of syn isomers 1a-c afforded the corresponding naphthalenes 8a-c in almost quantitative yields; in contrast, irradiation of anti isomers 2a-c gave complicated mixtures. The quantum yield of disappearance of 1a was 52 times that of 2a. Reaction mechanisms are proposed to account for the product formation. The differences in the photochemical behavior of the title syn and anti isomers are rationalized in terms of stereoelectronic effects of the epoxy rings in the syn isomers.     

Asymmetric synthesis of syn- and anti-1,3-amino alcohols

The first application of metalloenamines derived from N-sulfinyl imines is reported for the highly diastereoselective addition to aldehydes. Reduction of the beta-hydroxy-N-sulfinyl imine products with catecholborane and LiBHEt3 provides syn- and anti-1,3-amino alcohol derivatives, respectively, with very high diastereomeric ratios.     

Production and specificity of anti-22-oxacalcitriol antisera.

22-Oxacalcitriol 3-hemiglutarate, a haptenic derivative of 22-oxacalcitriol, was synthesized to obtain a specific antibody for use in radioimmunoassay. Three antisera were elicited in rabbits against the hapten conjugated with bovine serum albumin, and their specificity was examined by cross-reaction study. One of the antisera was found to be satisfactorily specific, and expected to provide a radioimmunoassay useful for the pharmacokinetic study of 22-oxacalcitriol.     

Nickel(II) complexes of anti-2-furancarboxaldoxime

Five different complexes of nickel(II) withanti-2-furancarboxaldoxime (-FDH) have been prepared and characterized by elemental analysis, molecular weights, conductance studies, magnetic moments and infra-red spectral studies. These are [Ni(FDH)₄Cl₂], [Ni(FD)₂(FDH)], [Ni(FD)₂(FDH)₂], [Ni(FD)₂·en], and [Ni(FD)₂]. All the complexes are neutral monomeric, paramagnetic (=3.3–3.7 B) and may be considered octahedral except the complex [Ni(FD)₂], (=2.92 B) which is tetrahedral. In these complexes the ligand functions as a monodentate and/or bidentate, coordinating with furan oxygen and oxime oxygen in the latter case. The ligand has been shown to be present in the ionized, and/or unionized form in these complexes.     

Regio- and stereospecific syntheses of syn- and anti-1,2-imidazolylpropylamines from the reaction of 1,1'-carbonyldiimidazole with syn- and anti-1,2-amino alcohols

The regio- and stereospecific conversion of syn- and anti-1,2-amino alcohols to their respective syn- and anti-1,2-imidazolylpropylamines via treatment with 1,1'-carbonyldiimidazole is described. The rationale behind the regio- and stereospecific nature as well as the generality of the reaction is discussed.     

Orbital interactions in anti- and syn- tricyclooctadienes and their homoderivatives

Photoelectron spectroscopy and molecular orbital calculations of the Extended Hückel, MINDO/3 and STO-3G Hartree-Fock type have been applied to anti- and syn-tricyclo[4.2.0.0^2,5]octadiene (1 and 2) and their homo and bishomo derivatives. The resulting ordering of the one-electron levels for 1 and 2 are 7a _g ( ₊), [6b _u (), 5b _u (_–)], 4a _u (), 3a _u () and 7a ₁(₊), 5b ₂(), 6b ₂(_–), 3a ₂(), 4b ₁(), respectively. The present results differ substantially from those previously published.     

An efficient entry to optically active anti- and syn-beta-amino-alpha-trifluoromethyl alcohols

The reaction of chiral 5,6-dihydro-2H-1,4-oxazin-2-ones with TMSCF3 in the presence of a suitable activator leads to trifluoromethyl lactols, which can be selectively reduced to anti-beta-amino-alpha-trifluoromethyl alcohols. The corresponding syn diastereoisomers are obtained when the starting imines are reduced and the nitrogen atom is conveniently protected. In addition, a novel rearrangement of the CF3 group in the lactol intermediates has been observed. This represents a formal CF3 addition to the imine function in the starting substrates.