Benzyl diesters

N-Benzyloxycarbonyl-L-aspartic acid-a-p-nitrophenyl, /3-benzyl Diester Hydrogen... 

A solution of 88.5 parts of L-phenylalanine methyl ester hydrochloride in 100 parts of water is neutralized by the addition of dilute aqueous potassium bicarbonate, then is extracted with approximately 900 parts of ethyl acetate. The resulting organic solution is washed with water and dried over anhydrous magnesium sulfate. To that solution is then added 200 parts of N-benzyloxycarbonyl-L-aspartic acid-a-p-nitrophenyl, -benzyl diester, and that reaction mixture is kept at room temperature for about 24 hours, then at approximately 65°C for about 24 hours. The reaction mixture is cooled to room temperature, diluted with approximately 390 parts of cyclohexane, then cooled to approximately -18°C in order to complete crystallization. The resulting crystalline product is isolated by filtration and dried to afford -benzyl N-benzyloxycarbonvI-L-aspartyl-L-phenylalanine methyl ester, melting at about 118.5°-119.5°C. 

Labetalol HCI 4-Benzyloxyaniline HCI Hydroxytryptophan N-BenzyloxycarbonyI-L-aspartic acid-a-nitrophenyl,/3-benzyl diester Aspartame... 

Labetalol HCI 4-Benzyloxyanillne HCI Hydroxytryptophan N-Benzyloxycarbonyl-L-aspartic acid-Ct-nitrophenyl,0-benzyl diester Aspartame... 

A/eso-benzylic diester complexes have been hydrolysed using pig liver esterase to give rise to the corresponding mono-ester analogue with high enantiomeric purity (Scheme 6.11). ... 

Porcine liver esterase (PLE) gives excellent enantioselectivity with both dimethyl 3-methylglutarate [19013-37-7] (lb) and malonate (2b) diester. It is apparent from Table 1 that the enzyme s selectivity strongly depends on the size of the alkyl group in the 2-position. The hydrolysis of ethyl derivative (2c) gives the S-enantiomer with 75% ee whereas the hydrolysis of heptyl derivative (2d) results in the R-monoester with 90% ee. Chymotrypsin [9004-07-3] (CT) does not discriminate glutarates that have small substituents in the 3-position well. However, when hydroxyl is replaced by the much bulkier benzyl derivative (Ic), enantioselectivity improves significantly. 

Allyl- -diathylester 204 Allyl-(2-methyl-allyl)- -diathylester 202 -amid-nitril (2,2-disubst.) 113 Amino- -diathylester 613 Benzyl- -diathylester 204, 208, 210 Benzyl- -dinitril 559 Benzyliden- -diathylester 208, 210 Benzyliden- -diathylester-nitril 206 Benzyliden- -dinitril 559, 643 ter.-Butyl- -nitril 114 Cyclohexyl- -athylester-nitril 206 Cyclohexyl- -diathylester 204 Cyclohexyl- -dinitril 559 Cyclohexyliden- -athylester-nitril 206 Cyclohexyliden- -dinitril 559 (1-Cyclopropyl-athyliden)- -dinitril 666 Diathyl- -amid-nitril 113 -diester 640... 

The benzyl phosphonate triesters 100 reacted with isocyanates under similar conditions to give the corresponding cyclic urea phosphonate diesters 101 (2). 

The synthesis of 5-phosphono-l,2,4-triazolin-3-one 137 began with the low-temperature metalation and phosphorylation (77) of the f-butyldimethylsilyl (TBDMS)-protectedlV-benzyl-tiiazolinone 134. The phosphonate diester 135 was obtained ter the silyl protecting group... 

Alcohols can be phosphorylated to phosphoric diesters by ionic phosphoric monoimidazolides in acetone at temperatures of about 50-60 °C over the course of several hours. These imidazolides are generally prepared by reaction of the appropriate phosphate with CDI (see Section 2.2). Reactions with ethyl, -butyl, w-pentyl, -octyl benzyl alcohol and various other alcohols have also been described.[1]... 

The most convincing evidence in favor of a uniform 3,5-diester linkage between nucleotides has been obtained by the action of various enzymes on synthetic diesters of known constitution.218 217 Ribonuclease and spleen extracts were found to act only on nucleoside 3-(benzyl hydrogen phosphates), but not on other isomers, to give nucleoside cyclic phosphates which are broken down further to give nucleoside 3-phosphates. It is concluded, by analogy, that polynucleotides, which are substrates for these enzymes, also possess ester groupings at the 3-positions, rather than at the... 

Lack of selectivity in the reaction of the /3-D-glucoside derivative with one molar equivalent of benzylthiocarbonyl chloride has also been noted 40% of the 2,3-diester and 40% of the starting material were isolated.40 Similarly, unimolar benzoylation of phenyl 4,6-0-benzylidene-/3-D-glucopyranoside gave only 9% of the 3-ester, together with 47% of the 2,3-diester.41 Acylation of benzyl 4,6-0-benzylidene-/8-D-glucopyranoside with acetic anhydride-pyridine-pyridine hydrochloride yielded,42 in contrast to the reaction with the... 

A more versatile procedure for the synthesis of mixed 1,2,5-triesters of 4, or of 2,5-diesters of 25, starts from the readily accessible 5-O - benzyl -1,2-0- isopropylidene - a -D-glucofuranurono-6,3-lactone34 (45) (see Section IX). 

Reaction of the sodium salt of a cyclic phosphite diester with a bis-benzylic halide... 

J. Boutelje, M. Hjalmarsson, K. Hult, M. Lindback, T. Norin, Control of the Stereoselectivity of Pig Liver Esterase by Different Reaction Conditions in the Hydrolysis of cw-iV-Benzyl-2,5-bismethoxycarbonylpyrrohdine and Structurally Related Diesters , Bioorg. Chem. 1988, 16, 364-375. 

It may be suspected that the genuinely topotactic (as secured by the molecular precision of the AFM [18]) photodimerization of 2-benzyl-5-benzyli-denecyclopentanone [118] might be a good candidate for a quantitative preparative photo dimerization to give the head-to-tail anti-[2+2] dimer. Early quantitative solid-state [2-1-2] photodimerizations (most of the published mechanistic interpretations of which can no longer be accepted) are listed in [110]. These deal with the anti dimerization of acenaphthylene-1,2-dicarboxylic anhydride, the head-to-head syn dimerization of acenaphthylene-1-carboxylic acid, the syn dimerization of 5,6-dichloroacenaphthylene, and the thermally reversible head-to-tail anti dimerization of seven ( )-2,6-di-f-butyl-4-(2-aryl-ethenyl)pyrylium-trifluoromethanesulfonates. All of these reactions proceed fully specific. On the other hand, quantitative photoconversions of a 1 1 mixed crystal of ethyl and propyl a-cyano-4-[2-(4-pyridyl)ethenyl]cinnamates gives mixtures of diesters with one (A>410 nm) or two cyclobutane rings (no cutoff filter). 

Warrener and co-workers (25) exploited a 1,3-dipolar cycloaddition reaction to synthesize a 7-azanorbornane 124 (Scheme 9.25). The cyclobutene-1,2-diester 121 underwent smooth cycloaddition with benzyl azide to give the triazohne 122, which... 

Der Curtius-Abbau geht von Malonsaure-monoestern aus, die iiber die Malonsaure-azid-ester zu racemischen a-Aminosaure-estern thermolysiert werden. Eine enantio-selektive Reaktion verwendet zur Verseifung der Malonsiiure-diester Chymotrypsin. Aus (R)-Benzyl-methylmalonsaure-monomethylester (98% ee) erhalt man z. B. (S)-y.-Methyl-phenylalanin1. 

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