scholarly journals Regioselective biocatalytic self-sufficient Tishchenko-type reaction via formal intramolecular hydride transfer

2020 ◽  
Vol 56 (47) ◽  
pp. 6340-6343
Author(s):  
Erika Tassano ◽  
Kemal Merusic ◽  
Isa Buljubasic ◽  
Olivia Laggner ◽  
Tamara Reiter ◽  
...  
Keyword(s):  
Hydride Transfer ◽  
Alcohol Dehydrogenases ◽  
Type Reaction ◽  
Hydride Shift ◽  
Sufficient Reduction

Alcohol dehydrogenases catalyze the regioselective lactonization of dialdehydes via a bio-Tishchenko-like reaction. The nicotinamide-dependent self-sufficient reduction–oxidation sequence proceeds through a formal intramolecular hydride shift.

Evidence for a Hydride Shift in the Alkaline Rearrangements of D-Ribose

1971 ◽  
Vol 49 (9) ◽  
pp. 1433-1440 ◽  
Author(s):  
W. B. Gleason ◽  
R. Barker
Keyword(s):  
Small Proportion ◽  
Hydride Transfer ◽  
Aqueous Alkali ◽  
Hydride Shift ◽  
Presence And Absence

The synthesis of D-ribose-2-t from D-arabinose is described and its conversions in aqueous alkali in the presence and absence of oxygen reported. In both situations a significant amount of label is transferred from C-2 to -1 and a relatively small proportion is released to the solvent. It is concluded that hydride transfer is occurring and that enolization, which requires the loss of hydrogen from C-2, is not an obligatory first step in base-catalyzed rearrangements of D-ribose.

Catalyst-free construction of spiro [benzoquinolizidine-chromanones] via a tandem condensation/1,5-hydride transfer/cyclization process

2020 ◽  
Vol 18 (43) ◽  
pp. 8839-8843
Author(s):  
Siyuan Liu ◽  
Hang Wang ◽  
Baomin Wang
Keyword(s):  
Hydride Transfer ◽  
Catalyst Free ◽  
Highly Efficient ◽  
Hydride Shift ◽  
Cyclization Process ◽  
Free Construction

A highly efficient and quite mild protocol to achieve spiro [benzoquinoline-chromanones] through a catalyst-free condensation/[1,5]-hydride shift/6-endo cyclization sequence was developed.

Impact of Protein Flexibility on Hydride-Transfer Parameters in Thermophilic and Psychrophilic Alcohol Dehydrogenases

2004 ◽  
Vol 126 (31) ◽  
pp. 9500-9501 ◽  
Author(s):  
Zhao-Xun Liang ◽  
Iason Tsigos ◽  
Vassilis Bouriotis ◽  
Judith P. Klinman
Keyword(s):  
Hydride Transfer ◽  
Protein Flexibility ◽  
Alcohol Dehydrogenases ◽  
Transfer Parameters

A one-pot catalyst/external oxidant/solvent-free cascade approach to pyrimidines via a 1,5-hydride transfer

2019 ◽  
Vol 21 (1) ◽  
pp. 69-74 ◽  
Author(s):  
Mohit L. Deb ◽  
Paran J. Borpatra ◽  
Pranjal K. Baruah
Keyword(s):  
Hydride Transfer ◽  
Cascade Reaction ◽  
Solvent Free ◽  
One Pot ◽  
Hydride Shift

A cascade reaction for synthesizing pyrimidines by the functionalization of the C–H bond adjacent to nitrogen through a 1,5-hydride shift is reported.

Ring Opening and Rearrangement of a Nitro-Capped Cobalt(III) Cage Complex With an N3S3 Donor Set

1994 ◽  
Vol 47 (5) ◽  
pp. 807 ◽  
Author(s):  
P Osvath ◽  
AM Sargeson
Keyword(s):  
Ring Opening ◽  
Hydride Transfer ◽  
Strong Acid ◽  
Amine Group ◽  
Type Reaction ◽  
Cage Complex ◽  
Methylene Unit ◽  
Excess Base

Treatment of the N3S3 donor cage complex [Co(NO2-capten)]3+ (1-methyl-8-nitro-3,13,16-trithia-6,10,19-triazabicyclo[6.6.6]icosanecobalt(III)) with excess base leads to deprotonation of a secondary coordinated amine group, followed by loss of a methylene unit from the cap by a retro-Mannich type reaction. Subsequent intermolecular hydride transfer gives a novel oxidized and partly delocalized macrocyclic complexed carbanion (13-(4-amino-2-thiabutyl)-13-methyl-6-nitro-1,11-dithia-4,8-diazacyclotetradec-4-enato(6)cobalt(III)) that is stabilized by deprotonation, and which remains deprotonated even in strong acid.

Direct Intermolecular C–H Functionalization Triggered by 1,5-Hydride Shift: Access to N-Arylprolinamides via Ugi-Type Reaction

2017 ◽  
Vol 19 (7) ◽  
pp. 1566-1569 ◽  
Author(s):  
Le Zhen ◽  
Jiankun Wang ◽  
Qing-Long Xu ◽  
Hongbin Sun ◽  
Xiaoan Wen ◽  
...  
Keyword(s):  
Type Reaction ◽  
Hydride Shift

Intramolecular hydride shift in some noncyclic isopropyl ketols

1981 ◽  
Vol 59 (4) ◽  
pp. 688-696 ◽  
Author(s):  
E. W. Warnhoff ◽  
Margaret Y. H. Wong ◽  
P. Sundara Raman
Keyword(s):  
Reaction Times ◽  
Hydride Transfer ◽  
Reformatsky Reaction ◽  
Tert Butyl ◽  
Hydride Shift ◽  
Aqueous Base ◽  
The Reformatsky Reaction

The acyclic ketols [Formula: see text] have been synthesized by a Reformatsky sequence. Each ketol undergoes intramolecular hydride transfer when refluxed in KOH–H2O–t-BuOH solution. When the procedure was applied to the synthesis of 34, hydride transfer occurred during the Reformatsky reaction to yield 33 instead. With longer reaction times, 33 underwent self-acylation and β-dicarbonyl cleavage to 37. Treatment of 33 with aqueous base gave a mixture of ketols 35 and 36 from hydride transfer and β-keto decarboethoxylation. The attempted conversion of the isobutyrate group of the Reformatsky intermediates 21 and 24 to tert-butyl was not practicable.

Deuterium labeling as a test of intramolecular hydride mechanisms in the fragmentation of 2-(1-hydroxybenzyl)-N1′-methylthiamin

2005 ◽  
Vol 83 (9) ◽  
pp. 1277-1280 ◽  
Author(s):  
Glenn Ikeda ◽  
Ronald Kluger
Keyword(s):  
Proton Transfer ◽  
Spectroscopic Analysis ◽  
Hydride Transfer ◽  
Fragmentation Reaction ◽  
Deuterium Labeling ◽  
Benzoylformate Decarboxylase ◽  
Hydride Shift ◽  
Benzoin Condensation ◽  
Normal Water ◽  
Amino Pyrimidine

2-(1-Hydroxybenzyl)-N1′-methylthiamin (1b) is a model for the addition intermediate in the thiamin catalyzed benzoin condensation. However, N-alkylation alters the reactivity of the compound: instead of undergoing base-catalyzed formation of benzaldehyde and N1′-methylthiamin, it rapidly forms trimethyl amino pyrimidine (2b) and phenylthiazole ketone (3). The base-catalyzed fragmentation process is faster than the analogous enzymic reaction (in benzoylformate decarboxylase) under the same conditions. One possible mechanism for the rapid fragmentation is an internal hydride transfer from α-C2 to the methylene bridge between the heterocycles. To test the hydride mechanism we prepared α-C2-deuterated 1b and conducted the fragmentation reaction in normal water. Spectroscopic analysis revealed that the trimethyl aminopyrimidine product does not contain any deuterium, ruling out a hydride transfer mechanism. This supports a mechanism for fragmentation that proceeds instead via a proton transfer from α-C2. Since protonation (and hence, deprotonation) of that site is part of the normal catalytic cycle of benzoylformate decarboxylase, the enzyme must divert the reaction from the lowest energy pathway since it would share a common intermediate with the fragmentation process.Key words: thiamin, fragmentation, benzoylformate decarboxylase, proton transfer, hydride shift.

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