Stereochemical Characterisation of the Non-Canonical α-Humulene Synthase from Acremonium strictum

The non-canonical fungal α-humulene synthase was investigated through isotopic labelling experiments for its stereochemical course regarding inversion or retention at C-1, the face selectivity at C-11, and the stereoselectivity of...

Search for nucleophilicity effect on the face selectivity of addition to a sterically unbiased ketone

The Journal of Organic Chemistry ◽

10.1021/jo00256a050 ◽

1988 ◽

Vol 53 (21) ◽

pp. 5155-5158 ◽

Cited By ~ 15

Author(s):

M. H. Lin ◽

J. E. Silver ◽

W. J. Le Noble

Keyword(s):

The Face ◽

Modification of the face selectivity in asymmetric induction by cyclodextrins through the formation of three-component inclusion compounds

Journal of Inclusion Phenomena and Macrocyclic Chemistry ◽

10.1007/bf01041579 ◽

1996 ◽

Vol 25 (1-3) ◽

pp. 249-252 ◽

Cited By ~ 2

Author(s):

E. Renard ◽

A. Deratani ◽

F. Djedaini-Pilard ◽

B. Perly

Keyword(s):

Inclusion Compounds ◽

Asymmetric Induction ◽

The Face ◽

On the mechanism of ophiobolin F synthase and the absolute configuration of its product by isotopic labelling experiments

Organic & Biomolecular Chemistry ◽

10.1039/d0ob01470b ◽

2020 ◽

Vol 18 (31) ◽

pp. 6072-6076 ◽

Cited By ~ 3

Author(s):

Zhiyang Quan ◽

Jeroen S. Dickschat

Keyword(s):

Absolute Configuration ◽

Isotopic Labelling ◽

The Absolute ◽

The cyclisation mechanism of ophiobolin F synthase AcldOS and the absolute configuration of its product were investigated by isotopic labelling experiments.

ChemInform Abstract: Diastereoselective Peracid Epoxidation: Control of the Face Selectivity via Functional Group Tuning and Proper Choice of Epoxidation Reagent.

ChemInform ◽

10.1002/chin.199831091 ◽

2010 ◽

Vol 29 (31) ◽

pp. no-no

Author(s):

A. J. JENSEN ◽

K. LUTHMAN

Keyword(s):

Functional Group ◽

Proper Choice ◽

The Face ◽

Role of glutamine synthetase in phenazine antibiotic production by Pantoea agglomerans Eh1087

Canadian Journal of Microbiology ◽

10.1139/w04-076 ◽

2004 ◽

Vol 50 (10) ◽

pp. 877-881 ◽

Cited By ~ 5

Author(s):

Matthew D Galbraith ◽

Stephen R Giddens ◽

H Khris Mahanty ◽

Bruce Clark

Keyword(s):

Glutamine Synthetase ◽

Antibiotic Production ◽

Amino Acid Sequences ◽

Pantoea Agglomerans ◽

Wild Type ◽

Isotopic Labelling ◽

High Degree ◽

Degree Of Similarity ◽

Pantoea agglomerans strain Eh1087 produces the phenazine antibiotic D-alanylgriseoluteic acid. A glutamine auxotroph harboring an insertion in a putative glnA gene was obtained by transposon-mutagenesis of Eh1087 that produced less D-alanylgriseoluteic acid than the parental strain (strain Eh7.1). Cosmids encoding the Eh1087 glnA were isolated by their ability to complement the mutant for prototrophy. The role of the Eh1087 glnA locus was functionally confirmed by complementation of an Escherichia coli glnA mutant. Analysis of the nucleotide and deduced amino acid sequences of the Eh1087 glnA gene indicated a high degree of similarity to the glnA genes and glutamine synthetase enzymes of other Enterobacteriaceae. Isotopic labelling experiments with 15N-labelled ammonium sulfate demonstrated that wild-type Eh1087 incorporated 15N into griseoluteic acid more readily than the glnA mutant Eh7.1. We conclude that the 2 nitrogens in the phenazine nucleus originate from glutamine and the intracellular glutamine synthesized by Eh1087 is a source of the phenazine nucleus nitrogens even in glutamine-rich environments.Key words: phenazine, Pantoea, Erwinia, glutamine synthetase, biosynthesis.

A Boron-Boron Double Transborylation Strategy for the Synthesis of gem-Diborylalkanes

10.26434/chemrxiv.11815830 ◽

2020 ◽

Author(s):

Jamie Docherty ◽

Kieran Nicholson ◽

Andrew P Dominey ◽

Stephen Thomas

Keyword(s):

Transition State ◽

Thermodynamic Parameters ◽

Terminal Alkynes ◽

Isotopic Labelling ◽

Wide Range ◽

Boronic Esters ◽

9-Borabicyclo[3.3.1]nonane (H-B-9-BBN) has been used as a catalyst for the sequential double hydroboration of alkynes with pinacolborane (HBpin) to give alkyl gem-di-pinacol boronic esters. This strategy, which is effective for a wide range of terminal alkynes, is predicated upon a key C(sp3)-B / B-H transborylation reaction. Transition-state thermodynamic parameters and 10-boron-isotopic labelling experiments are indicative of an σ-bond metathesis exchange pathway.

Modification of the Face Selectivity in Asymmetric Induction by Cyclodextrins through the Formation of Three-Component Inclusion Compounds

Proceedings of the Eighth International Symposium on Cyclodextrins ◽

10.1007/978-94-011-5448-2_145 ◽

1996 ◽

pp. 671-674

Author(s):

E. Renard ◽

A. Deratani ◽

F. Djedaini-Pilard ◽

B. Perly

Keyword(s):

Inclusion Compounds ◽

Asymmetric Induction ◽

The Face ◽

Isotopic Labelling Experiments and Enzymatic Preparation of Iso-Casbenes with Casbene Synthase from Ricinus communis

Organic Chemistry Frontiers ◽

10.1039/d1qo01707a ◽

2022 ◽

Author(s):

Heng Li ◽

Jeroen Dickschat

Keyword(s):

Ricinus Communis ◽

Enzyme Mechanism ◽

Enzymatic Preparation ◽

Isotopic Labelling ◽

Isotopic labelling experiments gave insights into the enzyme mechanism of casbene synthase from Ricinus communis, showing a clear stereochemical course for the cyclisation reaction, in agreement with the reported absolute...

Asymmetric induction in Diels–Alder reactions of α-alkoxyorthoquinodimethanes

Canadian Journal of Chemistry ◽

10.1139/v89-153 ◽

1989 ◽

Vol 67 (6) ◽

pp. 1010-1014 ◽

Cited By ~ 8

Author(s):

James L. Charlton ◽

Guy L. Plourde ◽

Glenn H. Penner

Keyword(s):

Molecular Orbital ◽

Geometry Optimization ◽

Diels Alder ◽

Asymmetric Induction ◽

Molecular Orbital Calculations ◽

Cycloaddition Reactions ◽

Vinyl Ethers ◽

The Face ◽

Face Selectivity ◽

Alkoxy Groups

It has been shown that dienophiles cycloadd selectively to one face of o-quinodimethanes (o-QDMs) bearing chiral α-alkoxy groups. The face selectivity (diastereoselectivity) increases for the series of chiral groups -OCH(Ph)CH3, -OCH(Ph)CH(CH3)2, and -OCH(Ph)C(CH3)3. A similar effect on the face selectivity of the Diels–Alder reactions of chiral alkoxy vinyl ethers for the same series of chiral groups has been noted previously by others. A mechanism has been proposed to explain the face selectivity in the cycloaddition reactions of the alkoxy o-QDMs. Abinitio molecular orbital calculations with geometry optimization on vinyl 1-phenylethyl ether to determine its lowest energy conformations support the proposed mechanism. The absolute stereochemistries of the o-QDM cycloadducts have been determined to verify the predictions of the model. Keywords: o-quinodimethanes, asymmetric, Diels–Alder, cycloaddition.