Titanium silicate molecular sieve, TS-1, catalysed C–C bond formation in Mukaiyama type aldol reactions

1996 ◽  
pp. 129-130 ◽  
Author(s):  
M. Sasidharan ◽  
Satya V. N. Raju ◽  
K. V. Srinivasan ◽  
Vincent Paul ◽  
R. Kumar
Keyword(s):  
Molecular Sieve ◽  
Bond Formation ◽  
Aldol Reactions ◽  
Titanium Silicate

ChemInform Abstract: Titanium Silicate Molecular Sieve, TS-1, Catalyzed C-C Bond Formation in Mukaiyama Type Aldol Reactions.

ChemInform ◽  
2010 ◽  
Vol 27 (22) ◽  
pp. no-no
Author(s):  
M. SASIDHARAN ◽  
S. V. N. RAJU ◽  
K. V. SRINIVASAN ◽  
V. PAUL ◽  
R. KUMAR
Keyword(s):  
Molecular Sieve ◽  
Bond Formation ◽  
Aldol Reactions ◽  
Titanium Silicate

scholarly journals Catalytic Cascade Reactions Inspired by Polyketide Biosynthesis

2020 ◽  
Vol 74 (9) ◽  
pp. 699-703
Author(s):  
Daniel Moser ◽  
Alessandro Castrogiovanni ◽  
Dominik Lotter ◽  
Reto M. Witzig ◽  
Vincent C. Fäseke ◽  
...  
Keyword(s):  
Chemical Synthesis ◽  
Bond Formation ◽  
Cascade Reactions ◽  
Aldol Reactions ◽  
Biological Functions ◽  
Polyketide Biosynthesis ◽  
Stepwise Approach ◽  
Natural Systems ◽  
Carbon Carbon Bond ◽  
Enzymatic Machinery

Aldol reactions belong to the most important methods for carbon–carbon bond formation and are also involved in one of the most astonishing biosynthetic processes: the biosynthesis of polyketides governed by an extraordinarily sophisticated enzymatic machinery. In contrast to the typical linear or convergent strategies followed in chemical synthesis, this late-stage catalysis concept allows Nature to assemble intermediates that are diversified into a broad range of scaffolds, which assume various crucial biological functions. To transfer this concept to small-molecule catalysis to access products beyond the natural systems, a stepwise approach to differentiate increasingly complex substrates was followed by investigating arene-forming polyketide cyclizations. An outline of our efforts to develop and apply these concepts are presented herein.

ChemInform Abstract: Titanium Silicate Molecular Sieve (TS-1) Induced Catalytic Cleavage of Tosylhydrazones.

ChemInform ◽  
2010 ◽  
Vol 25 (9) ◽  
pp. no-no
Author(s):  
P. KUMAR ◽  
V. R. HEGDE ◽  
B. PANDEY ◽  
T. RAVINDRANATHAN
Keyword(s):  
Molecular Sieve ◽  
Titanium Silicate ◽  
Catalytic Cleavage

Ephedrines as Chiral Auxiliaries in Enantioselective Alkylation Reactions of Acyl Ephedrine Amides and Esters: A Review

2018 ◽  
Vol 15 (1) ◽  
pp. 38-83 ◽  
Author(s):  
Alejandro Cruz ◽  
Itzia I. Padilla-Martínez ◽  
Maria E. Bautista-Ramirez
Keyword(s):  
Asymmetric Synthesis ◽  
Bond Formation ◽  
Alkyl Halides ◽  
Aldol Reactions ◽  
Alkylation Reaction ◽  
Chiral Auxiliaries ◽  
Asymmetric Alkylation ◽  
Chiral Compounds ◽  
High Yields ◽  
Alkylation Reactions

Background: In modern chemistry, the asymmetric synthesis for the preparation of high purity chiral compounds to be used as pharmaceuticals or additives in foods have been of capital importance. Chiral auxiliary reagents are used to control the stereochemistry of the reaction in the generation of new chiral compounds, in this context, Ephedra compounds (ephedrines and pseudoephedrines) and some of their derivatives have been broadly used as chiral ligands in catalysis or chiral inductors in asymmetric synthesis. Objective: This review focuses on recent progress in the use of ephedra compounds and their N-substituted derivatives as chiral auxiliaries in the area of asymmetric synthesis, via the alkylation reaction of the enolates derived from their corresponding N-Acyl or O-Acyl derivatives, in the C-C bond formation. Conclusion: A vast amount of work has been done about the use of ephedra compounds in asymmetric synthesis area, in general, it was found that pseudoephedrines are much more effective than ephedrines and are preferred as chiral auxiliaries in the asymmetric alkylation of the corresponding N-acyl amides or O-Acyl esters. Alkylation with alkyl halides requires the use of more than 4 equivalents of LiCl to accelerate the alkylation rate and to complete the reaction without effecting the diastereoselectivity of the process. In contrast, the use of secondary alkyl halides was found to make the reaction very slow. Furthermore, a lot of work about the alkylation reaction in the opening of epoxides and aziridines, aldolic condensation, Manich reaction, addition of nucleophiles to α,β-unsaturated ephedrine amides and Michael additions have been demonstrated to be effective in the C-C bond formation. The aldol reaction of chiral enolates, proceeds with decreasing yields and enantioselectivities as the steric demand of the α-R of ephedrine amides and the size of carbonyl compound increase. In addition, the use of branched groups on N,N-disubstituted norephedrine esters is highly recommended in the aldol reactions of aromatic and aliphatic aldehydes.In the case of N-Acyl or O-Acyl ephedrines supported on polymers, the reaction proceed with good enantioselectivities but low yields, the enantioselectivities are goods but the yields are low. In general, the removal step of the auxiliary proceeds with low to high yields but without epimerization.

ChemInform Abstract: Molecular Sieve Mediated Decarboxylative Mannich and Aldol Reactions of β-Ketoacids.

ChemInform ◽  
2013 ◽  
Vol 44 (47) ◽  
pp. no-no
Author(s):  
Fangrui Zhong ◽  
Chunhui Jiang ◽  
Weijun Yao ◽  
Li-Wen Xu ◽  
Yixin Lu
Keyword(s):  
Molecular Sieve ◽  
Aldol Reactions

Epoxidation of Styrene over a Titanium Silicate Molecular Sieve TS1 Using Dilute H2O2 as Oxidizing Agent

1995 ◽  
Vol 156 (1) ◽  
pp. 163-166 ◽  
Author(s):  
S.B. Kumar ◽  
S.P. Mirajkar ◽  
G.C.G. Pais ◽  
P. Kumar ◽  
R. Kumar
Keyword(s):  
Molecular Sieve ◽  
Oxidizing Agent ◽  
Titanium Silicate
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