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HT ht HT ht The first observation is that to the previously predicted I i values of B 9 b (301.5), B 10 b (294.0 ppm), and B 11 b (373.6 ppm), ZORA yield closer values of 286.8, 286.7, and 371.6 ppm ( I i = -14.7, -7.3, and -2.0 ppm, respectively). The dibromo derivative B 14 b has two different phosphorus atoms, one linked to two bromine atoms ( I i = I i SB ZORA sb - I i SB GIAO sb = 362.1 - 238.6 = 123.5 ppm) and the others to two hydrogen atoms ( I i = I i SB ZORA sb - I i SB GIAO sb = 335.3 - 340.1 = -4.8 ppm). [Extracted from the article]

Several new 4-substituted glutamic acid derivatives are described: 4-phosphinomethyl glutamic acid derivatives were prepared starting from (2S)-N-Boc-tert-butyl-4-methylene glutamate. The 4-carboxymethyl and 4-aminomethyl glutamic acid derivatives were obtained using asymmetric 1,4-addition conjugate of the enolate of Schiff base 1 to unsaturated esters. [Copyright &y& Elsevier]

We have shown that condensation of l-cysteine methyl ester (8) and l-threonine methyl ester (11) with formaldehyde provides a convenient and efficient access to novel heterocyclic 2:3 adducts. Depending on the amino acid, the condensation leads to either the N,N′-methylenebis(thiazolidine) (10, l-cys) or -(oxazolidine) (13, l-thr) derivative or to its bicyclo[4.4.1]undecane isomer (5, l-ser) as the major product of the reaction. The structure of 10, 12 and 13, was unambiguously confirmed by diffraction analysis and/or NMR spectroscopy. The latter proved to be a powerful tool to discriminate between the two possible isomers. X-Ray data emphasized the contribution of stereoelectronic effects to the structure of the above compounds. [Copyright &y& Elsevier]

Abstract: A comparative study of the Mitsunobu reaction at C1 and C6 positions of mannose using bis(2,2,2-trifluoroethyl) malonate as nucleophile is disclosed. While C-alkylation was predominant at the C6 position, only O-alkylation occurred at the anomeric position of the carbohydrate. Some factors playing a role in the selectivity of the reaction are discussed and an inverse mechanism of the Mitsunobu reaction for the anomeric position is proposed. [Copyright &y& Elsevier]

Abstract: Unprecedented magnesium dihalide-catalysed Claisen rearrangement of 2-alkoxycarbonyl allyl vinyl ethers derived from α-chloroglycidic esters is reported in the glucidic series. A first application of this reaction concerns the stereoselective construction of a disaccharide analogue including a galactosyl and an ulosonic isopropyl ester moieties. [Copyright &y& Elsevier]

Two new furanoid sesquiterpenoid ketones were isolated from the wood essential oil of Myoporum crassifolium from New Caledonia and characterized by their 1H- and 13C-NMR spectra. Besides these components, which represent about 12% of the oil, the sample was characterized by a high content (65.1%) of (−)-epi- α-bisabolol [or (−)-anymol] and its oxide derivatives. Copyright © 2005 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Presents an example of chiral molecular tweezers with a bis-Troger's base skeleton. Analogues of Troger's bases; Determination of the molecular structure by x-ray crystallography; Recognition of planar molecules based on noncovalent interactions.