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Benzoyl Group (benzoyl + group)
Selected AbstractsExtended application of a chiral stationary phase based on (+)-(18-crown-6)-2,3,11,12-tetracarboxylic acid to the resolution of N -(substituted benzoyl)-,-amino acid amidesJOURNAL OF SEPARATION SCIENCE, JSS, Issue 10 2006Guanghui Tan Abstract A chiral stationary phase (CSP 1) based on (+)-(18-crown-6)-2,3,11,12-tetracarboxylic acid was applied to the resolution of N -(substituted benzoyl)-,-amino acid amides and esters. N -(Substituted benzoyl)-,-amino acid amides were well resolved using a mixture of acetic acid-triethylamine-acetonitrile (0.01 : 0.05 : 100, v/v/v) as an optimum mobile phase while N -(substituted benzoyl)-,-amino acid esters were not resolved at all. In contrast, both N -(substituted benzoyl)-,-amino acid amides and esters were not resolved at all or resolved very poorly on another CSP (CSP 2), which lacks the two N,H hydrogens of the amide tethers of CSP 1. Among the substituents on the benzoyl group of analytes, the nitro group was the best for good resolution of analytes on CSP 1. From these results, the two N,H hydrogens of the amide tethers of CSP 1, the carbonyl oxygen of the amide group of analytes, and the nitro group on the benzoyl group of analytes were concluded to play significant roles in chiral recognition. In addition, various N -(3,5-dinitrobenzoyl)leucine amides with different lengths of N -alkylamide chains were resolved on CSP 1 and N -(3,5-dinitrobenzoyl)leucine N -propylamide was found to show the best chiral recognition in terms of the separation (, = 1.30) and the resolution factor (RS = 3.17). [source] Preparation and Reactions of 1,3-Diphosphacyclobutane-2,4-diyls That Feature an Amino Substituent and/or a Carbonyl GroupCHEMISTRY - A EUROPEAN JOURNAL, Issue 11 2004Hiroki Sugiyama Abstract The preparation and properties of a 1-amino-1,3-diphosphacyclobutane-2,4-diyl and a 1-benzoyl-1,3-diphosphacyclobutane-2,4-diyl, which can be regarded as functionalized cyclic biradical derivatives, were investigated. Hydrolysis of 1-diisopropylamino-3-methyl-2,4-bis(2,4,6-tri- tert -butylphenyl)-1,3-diphosphacyclobutane-2,4-diyl (7), which is formed by reaction of Mes*CP (4; Mes*=2,4,6- tBu3C6H2) with lithium diisopropylamide and iodomethane, resulted in ring-opening of the 1,3-diphosphacyclobutane-2,4-diyl skeleton, as well as de-aromatization of one of the Mes* rings. 3-Oxo-1,3-diphosphapropene 8 and 7-phosphabicyclo[4.2.0]octa-1(8),2,4-triene 9 were the resultant products, and these were subsequently characterized. Isomerization and oxidation of 7 occurred in the presence of TEMPO (2,2,6,6-tetramethyl-1-piperidinoxy) to give the first example of a cyclic dimethylenephosphorane derivative, namely 3-oxo-1,3-diphospha-1,4-diene 10. 1-Benzoyl-3- tert -butyl-2,4-bis(2,4,6-tri -tert -butylphenyl)-1,3-diphosphacyclobutane-2,4-diyl (12) was isolated and characterized from the reaction of 4 with tert -butyllithium and benzoyl chloride. Compound 12 was subsequently heated and underwent rearrangement of the benzoyl group and ring-expansion to afford 1-oxo-1H -[1,3]diphosphole 13. Reaction of 4 with lithium diisopropylamide and benzoyl chloride afforded the 2H -[1,2,4]oxadiphosphinine 15, which was probably formed through the 1,3-diphosphacyclobutane-2,4-diyl intermediate 14. Thermolysis of 15 afforded 1-oxo-1H -[1,3]diphosphole 16 in an Arbuzov-type rearrangement. [source] Donor-Bound Glycosylation for Various Glycosyl Acceptors: Bidirectional Solid-Phase Semisynthesis of Vancomycin and Its DerivativesCHEMISTRY - AN ASIAN JOURNAL, Issue 1 2007Takayuki Doi Prof. Abstract The glycosidation of a polymer-supported glycosyl donor, N -phenyltrifluoroacetimidate, with various glycosyl acceptors is reported. The application of the polymer-supported N -phenyltrifluoroacetimidate is demonstrated in the synthesis of vancomycin derivatives. 2- O -[2-(azidomethyl)benzoyl]glycosyl imidate was attached to a polymer support at the 6-position by a phenylsulfonate linked with a C13 alkyl spacer. Solid-phase glycosidation with a vancomycin aglycon, selective deprotection of the 2-(azidomethyl)benzoyl group, and glycosylation of the resulting 2-hydroxy group with a vancosamine unit were performed. Nucleophilic cleavage from the polymer support with acetate, chloride, azido, and thioacetate ions provided vancomycin derivatives in pure form after simple purification. The semisynthesis of vancomycin was achieved by deprotection of the acetate derivative. [source] Chiral ureas with two electronegative substituents at 1-N: An unusual case of coexisting pyramidal and almost planar 1-N atoms in the same crystal,CHIRALITY, Issue 7 2009Oleg V. Shishkin Abstract XRD studies of structure of N -acetoxy- N -methoxyurea and N,N -bis(methoxycarbonyl)- N -methoxyimide have revealed that in N -methoxy- N -X-ureas (X = OAc, Cl, OMe, N+C5H5) the additional shortening of NOMe bond took place, which arising from an nO(Me) -,*NX anomeric orbital interaction. XRD studies of N -chloro- N -ethoxyurea crystal have revealed the presence of two kinds of anomeric nitrogen configuration in the ONCl group in the form of a pyramidal configuration and a planar configuration for same 1-N nitrogen atom. XRD studies of N -4-chlorobenzoyloxy- N -ethoxyurea have revealed that the degree of pyramidality of the 1-N nitrogen in N -aroyloxy- N -alkoxyureas is tuned by orientation of benzoyl group with respect to the NO bond, which in turn depends of size of N -alkoxy group. Chirality, 2009. © 2008 Wiley-Liss, Inc. [source] | ||||||||||