Search results for "Alcohol"

1978

Synthesis and characterization of polymeric derivatives of the folic acid antagonist, Methotrexate, N-[4-(N-methyl-2,4-diamino-6-pteridinylmethylamino)benzoyl] glutamic acid (1a), a widely used antitumor agent, are described. Derivatives of poly(L-lysine), poly(iminoethylene), poly(vinyl alcohol), and carboxymethylcellulose with various contents (3–15 mole-%) of substituted repeating units were prepared by polymer-analogous amidation and transesterification of the dimethyl ester of 1a and with N-[2-(N-methylmorpholinio)ethyl]carbodiimide p-toluenesulfonate as coupling reagent. By nucleophilic addition reactions of the pteridinyl amino groups under mild conditions, 1a was bound without cross…

Ontogenetic variations of some enzymes indicentrarchus labrax(Serranidae)

1989

Abstract The ontogenesis of isozyme patterns of alcohol dehydrogenase (ADH), glycerol‐3‐phosphate dehydrogenase (α‐GPDH), lactate dehydrogenase (LDH), malate dehydrogenase (MDH), glucose‐6‐phosphate dehydrogenase (G‐6‐PD) and glucosephosphate isomer‐ase (GPI) in Dicentrarchus labrax was studied. ADH is active only in the liver of the adult; a‐GPDH is active in only two tissues in the adult: the A2 isozyme in white skeletal muscle and the B2 isozyme in the liver. Differential gene expression was found only for LDH, MDH and GPI, which have polymeric structure. The LDH, MDH and GPI isozymes 30 days after hatching were completely active and showed patterns very similar to those of the adult. Sp…

Enzyme-mediated enantioselective acylation of secondary amines in organic solvents

1991

Abstract Porcine pancreatic lipase (PPL) and lipase Amano P catalyze the enantioselective acylation of cyclic 1,2- and 1,3-amino alcohol derivatives in organic solvents. The enatiomeric excesses (ee′s) were shown to depend on the enzyme, reaction time, temperature and type of substrate.

Lipase-enhanced activity in flavour ester reactions by trapping enzyme conformers in the presence of interfaces

1998

In order to improve the lipase-catalyzed synthesis of flavour esters, we have used the reported strategy of interfacial activation-based molecular (bio)imprinting [Mingarro et al. 1995. Proc. Natl. Acad. Sci. U.S.A. 92: 3308], later called trapping in the presence of amphiphile interfaces (TPI) [Mingarro et al. 1996. Biochemistry 35: 9935]. Five lipases of fungal and mammalian origin typically used for esterification process have been explored to improve production by TPI treatment. A marked enhancement of enzymatic activity has been observed in all TPI-treated lipases assayed and the activation factor obtained was up to 90-fold. The dependence on chain length of acyl donors in the esterifi…

Polymer ester von sären des phosphors, 7. Polymerisation des 1-oxo-2,6,7-trioxa-1-phosphabicyclo[2.2.1]heptans

1981

1-Oxo-2,6,7-trioxa-1-phosphabicyclo[2.2.1]heptane is transformed in situ (prepared from trimethyl phosphite and glycerol) at −78°C in the presence of a trace of water into a crosslinked polymer containing constitutional repeating units with 5- and 6-membered rings. The reaction with reagents containing hydroxyl groups (water, acetic acid, alcohol) leads to the degradation of the network with the formation of soluble fragments with Pn = 35–50. This reactivity and the possibility to obtain other derivatives from the fragments make this polymer a carrier for pharmacologically active polymers with the advantage of decomposing only into the innocuous components phosphoric acid and glycerol.

STUDIEN ZUM VORGANG DER WASSERSTOFFÜBERTRAGUNG 621HERSTELLUNG UND ELEKTROREDUKTIVE SPALTUNG EINIGER ARYLDISULFONSÄUREDERIVATE

1982

Abstract Benzene-disulfonylchlorides were converted to the corresponding dialkyl-and diphenylesters, N-alkyl-and N-aryl disulfonamides. The half-wave-potentials E1/2 1 and E1/2 2 were measured and the products obtained on potentiostatic fission at E1/2 1 were isolated and characterized. The electroreduction of benzene-1,4-disulfonic acid-diphenylester in methanol yields phenol in a quantity approximately corresponding to the current passed, but no corresponding quantity of sulfinic acid. In dry acetonitrile, benzene-1,4-disulfonic acid diesters and diamides undergo potentiostatic fission (at E1/2 1) in good chemical and current yields, giving the corresponding monosulfonate-sulfinic acid or…

Fluorous TBAF: A Convenient and Selective Reagent for Fluoride-Mediated Deprotections

2009

A fluorous analogue of TBAF has been developed for its use in the clean removal of silicon-derived protecting groups. Purification of the crude mixtures by fluorous solid-phase extractions allowed alcohols, amines, and carboxylic acids to be obtained in high purity, with no need of chromatographic separations. The moderate reactivity of fluorous TBAF was exploited in selective deprotections of several bifunctional molecules.

Über eine Reaktion vono-Hydroxybenzylalkoholen mit Estern von Säuren des Phosphors mit der Koordinationszahl 3

1978

Abstract o-Hydroxybenzyl alcohol reacts with trimethyl phosphite under smooth conditions to o-hydroxyphenylmethane phosphonic acid dimethyl ester. This unusual reaction is of widest applicability. Derivatives of o-hydroxybenzyl alcohol independent of type, number or position of substituents in the ring, react with alkyl esters of phosphorous, phosphonous or phosphinous acids in an analogous process, forming the corresponding o-hydroxyphenylmethane phosphonic or phosphinic esters or phosphine oxides.

Enzymatic Resolution of 3-oxodicyclopentadiene on a Decagram Scale

2018

The chiral building block 3-oxodicyclopentadiene (1) can be readily resolved on a decagram scale by a short sequence consisting of (1) reduction to the corresponding endo-alcohol, (2) enzymatic oxidative resolution with a ketoreductase enzyme to give (+)-1 and the (+)-form of the endo-alcohol, and (3) reoxidation of the (+)-endo-alcohol with another ketoreductase to give (–)-1. With a selectivity factor of 310, the enantiomeric ratios of the resolved (+)-endo-alcohol and (+)-ketone are both >99:1. Both enzymatic oxidations could be performed with a at least 300:1 substrate/catalyst ratio (w/w).

Organocatalytic enantioselective synthesis of trifluoromethyl-containing tetralin derivatives by sequential (hetero)Michael reaction–intramolecular n…

2017

The enantioselective synthesis of tetralin derivatives bearing a trifluoromethylated all‐carbon quaternary stereocenter has been accomplished through a synthetic sequence comprising an organocatalytic β‐functionalization of ortho‐1‐trifluoromethylvinyl‐(hetero)aromatic conjugated aldehydes followed by the intramolecular nitrone 1,3‐cycloaddition reaction (INCR). Both nitromethane and N‐Cbz‐hydroxylamine were employed as nucleophiles in the initial organocatalytic conjugate addition step, which provided the chiral information required for the subsequent diastereoselective INCR. Although diastereoselectivity was moderate, good yields and enantioselectivities were, in general, obtained. Intere…