The first reagent-controlled asymmetric halolactonizations. Dihydroquinidine-halogen complexes as chiral sources of positive halogen ion

1998 ◽  
Vol 76 (9) ◽  
pp. 1233-1237 ◽  
Author(s):  
Robert B Grossman ◽  
Robert J Trupp
Keyword(s):  
Key Words ◽  
Carboxylic Acids ◽  
Factors Affecting ◽  
Unsaturated Carboxylic Acids

The first reagent-controlled asymmetric halolactonizations are described. Complexes of I+ with O-acyl- and O-aryldihydroquinidines are used to promote the asymmetric halolactonization of prochiral θ, δ-unsaturated carboxylic acids with low but measurable and reproducible enantioselectivity. Experimental factors affecting the ee's are described. Key words: halocyclization, halogenation, halonium ions, chiral, stereoselective.

Studies on enolate chemistry of 8-thiabicyclo[3.2.1]- octan-3-one: enantioselective deprotonation and synthesis of sulfur analogs of tropane alkaloids

2001 ◽  
Vol 79 (11) ◽  
pp. 1792-1798 ◽  
Author(s):  
Marek Majewski ◽  
Marc DeCaire ◽  
Pawel Nowak ◽  
Fan Wang
Keyword(s):  
Acetic Anhydride ◽  
Key Words ◽  
Carboxylic Acids ◽  
Alkylating Agents ◽  
Tropane Alkaloids ◽  
Lithium Amides ◽  
Lithium Enolate ◽  
Unsaturated Carboxylic Acids ◽  
Derivatives Of ◽  
Enantioselective Deprotonation

Enantioselective deprotonation of 8-thiabicyclo[3.2.1]octan-3-one (1) with chiral lithium amides, followed by reactions with electrophiles affords sulfur analogs of tropane alkaloids of pyranotropane family. Thus, deprotonation of 1 with (S)-N-(diphenyl)methyl-1-phenylethylamine (11d), followed by the reaction of the resulting nonracemic enolate with benzaldehyde gives the corresponding aldol product as one diastereoisomer (exo, threo) and in high enanatiomeric purity (95% ee). Trimethylsilyl chloride, acetic anhydride, and acyl cyanides react readily with the lithium enolate to give the corresponding derivatives of 1, however common alkylating agents fail to provide C-alkylated products. The reaction with acyl cyanides derived from α,β-unsaturated carboxylic acids (e.g., cinnamoyl cyanide) can be utilized in synthesis of thia-analogs of tropane alkaloids physoperuvine and isobellendine (13, 15).Key words: enantioselective deprotonation, tropane alkaloids.

ANALYSIS OF INNOVATION ACTIVITIES OF ENTERPRISES OF KAZAKHSTAN

2020 ◽  
Vol 384 (2) ◽  
pp. 137-145
Author(s):  
Zh. Abylkassimova ◽  
G. Orynbekova ◽  
М. Alibayeva ◽  
O. Osadchaya
Keyword(s):  
Key Words ◽  
Added Value ◽  
Human Potential ◽  
Innovation Activity ◽  
Factors Affecting ◽  
Innovation Potential ◽  
Innovation Activities ◽  
Innovation Economy

The article noted that the development of the innovation potential of enterprises in the regions of Kazakhstan contributes to the transition of the innovation economy, where goods with high added value will be produced. The article examines the factors affecting the innovation activity of the regions, considers the dynamics of innovation activity and identifies problems and tools for the development of innovative entrepreneurship. Key words: innovation, innovation activity, region, industrialization, human potential, infrastructure

Perturbation theory of substituent effect. Importance of the field effect in transmission of the substituent effect

1980 ◽  
Vol 45 (6) ◽  
pp. 1655-1661 ◽  
Author(s):  
Robert Ponec
Keyword(s):  
Perturbation Theory ◽  
Carboxylic Acids ◽  
Quantum Chemical ◽  
Substituent Effect ◽  
Field Effect ◽  
Adequate Description ◽  
Meta Position ◽  
Unsaturated Carboxylic Acids

Various quantum chemical approaches to the problem of transmission of the substituent effect were compared. It was shown that inclusion of the electronic repulsion (field effect) was necessary to give a true picture of differences in ρ constants for reactions of the cis and trans isomers of substituted unsaturated carboxylic acids; the same holds for an adequate description of transmission of the substituent effect from the meta position on a given skeleton.

scholarly journals A solvent-dependent chirality-switchable thia-Michael addition to α,β-unsaturated carboxylic acids using a chiral multifunctional thiourea catalyst

2020 ◽  
Vol 11 (21) ◽  
pp. 5572-5576 ◽  
Author(s):  
Noboru Hayama ◽  
Yusuke Kobayashi ◽  
Eriko Sekimoto ◽  
Anna Miyazaki ◽  
Kiyofumi Inamoto ◽  
...  
Keyword(s):  
Carboxylic Acids ◽  
Tertiary Amine ◽  
Michael Addition ◽  
Arylboronic Acid ◽  
Unsaturated Carboxylic Acids

An asymmetric thia-Michael addition of arylthiols to α,β-unsaturated carboxylic acids using a thiourea catalyst that bears arylboronic acid and tertiary amine moieties is reported.

Nickel-Catalyzed Decarboxylative Difluoroalkylation of α,β-Unsaturated Carboxylic Acids

2016 ◽  
Vol 55 (10) ◽  
pp. 3491-3495 ◽  
Author(s):  
Gang Li ◽  
Tao Wang ◽  
Fan Fei ◽  
Yi-Ming Su ◽  
Yan Li ◽  
...  
Keyword(s):  
Carboxylic Acids ◽  
Unsaturated Carboxylic Acids
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