Eliel, is a longstanding, successful series covering the most important advances in the field. A new generation in publishing, parallel to a new generation in Stereochemistry mandated a new venue and modus operandi for Topics. Zurich, the home of Werner and Wislicenus, has a unique heritage in Stereochemistry. Fortunately, the Wiley family's publishing partnerships include Verlag Helvetica Chimica Acta, a house with a reputation for superior quality in publishing.
Indeed, within the pages of its namesake periodical, Helvetica Chimica Acta, one finds many of the seminal research works of stereochemistry's giants. As such, a transfer of editorial operations to Zurich and a collaboration bringing Topics as a series closer to periodical status provides a growth platform for the future. About The Author.
Topics in Stereochemistry, Volume 15
Robert E. He received his undergraduate degree B. After his stay as a research associate at the University of North Carol Select Parent Grandparent Teacher Kid at heart. Age of the child I gave this to:. Hours of Play:.
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Carlier, Danny C. A mechanism in which the cyclopropyl C retains its asymmetry is presented. The results indicate that there is an energy barrier to the rehybridization of the electron pair from a hybridized orbital into a p-orbital I-strain. Under the identical conditions used to study the racemization of I, k1 for 2-methyl-3,3-diphenylpropionitrile II is 1.
Cyclopropyl anion. The rate of H-D exchange and rate of racemization of 2,2-diphenylcyclopropylnitrile I and its acyclic analog 2-methyldiphenylpropionitrile II were investigated. In contrast, extensive racemization was obsd. These observations in conjunction with results of ancillary studies show that proton abstraction by base is not rate-detg.
Tetrahedron , 61 , — DOI: Elsevier B.
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This review surveys the reactions and syntheses of cyclic, aliph. Among the myriad reactions of nitriles, the focus is on anionic reactions of nitriles that are significantly different from those of related electron-withdrawing groups. The review is partitioned into five main sections beginning with an overview of the structural features of nitriles as a prelude to understanding their unique properties. Syntheses of cyclic nitriles are then surveyed, followed by stereoselective alkylations, and cyclizations of cyclic nitriles, and concluding with methods for removing the nitrile group.
These expts. The intermediate formed is the first metalated nitrile demonstrated to possess macroscopic configurational stability. Herein we report Eyring analyses and reaction order studies of the racemization of enantioenriched Grignard reagent, chloro[ 1S cyano-2,2-diphenylcyclopropyl]magnesium, 2 in ethereal solvents. A highly neg. These results are consistent with an ion-pair sepn. Chiral organometallic reagents are useful in asym. The epimerization of a chiral Grignard reagent, prepd.
This compd. Epimerization rate consts. Studies were also performed at varying concns. Remarkable dynamic range in ktc was seen: relative to reaction at 0. Thus, the identity and concn. Reaction stoichiometry expts. Tetrahedron , 69 , — and references cited therein. Mycka, Robert J. Elsevier Ltd. Mechanistic expts. Collectively these alkylations; are the first electrophile-dependent alkylations of acyclic nitriles, exhibit a unique influence on the nature of the Grignard used for the deprotonation, and address the challenge of installing quaternary centers in conformationally mobile, acyclic nitriles.
The dependence of the stereochem. This hypothesis was supported by NMR spectroscopic studies, which permit one to assign a chelated pyramidal structure to the sodium benzylic carbanions and an almost planar naked carbanionic structure to the potassium benzylic carbanions generated in the presence of crown-6 ether. Remarkable effect of metal cations. Possible reasons for the striking effect of the nature of the metal catio on the stereochemistry of alkylation are discussed.
Cation and solvent effects in the alkylation of butyrophenone. CA 53, h; 54, e. The rates of alkylation of ethereal solns. The rate increased by more than times as the cation was varied from Li to K. Tetraalkylammonium salts were powerful catalysts. The reaction exhibited autocatalysis by the ketonic product. Ebulliometric studies of sodiobutyrophenone indicated an av. Alkylation within a co.
Structural studies on the alkali metal derivatives of 1- and 2-methylnaphthalene. C-metal bonding in 1-and 2-naphthylmethyl lithium, -sodium, and -potassium was examd. In THF, the chem. Appreciable barriers to rotation about the ring-methylene bonds in the anions showed that the partial delocalization was not due to rapid equil.
Lack of cation dependence of the spectra of the Li and Na compds. The spectra of the Li compds. Mitchell, Emily A. Transition metal-catalyzed reactions involving other intermediates have been treated as a sep. Beng, Timothy K. A highly diastereoselective methodol. Depending on the position of the C-Zn bond relative to the nitrogen position 2 vs position 4 , the stereoselectivity of the coupling can be directed toward either the trans- or cis-2,4-disubstituted products.
A novel 1,2-migration of Pd further expands this method to the stereoselective prepn.
Krishnan, Shyam; Bagdanoff, Jeffrey T. The insertion reaction of an aryne generated from a silylphenyl triflate into a oxoindanecarboxylate is used as a key step in the prepn. The methodol. By this methodol. Both cis and trans 2,6-disubstituted diastereoisomers can be prepd. In the case of 3-methoxy-Boc-piperidine, elimination of methoxide occurs upon lithiation, and with cis-2,4-disubstituted Boc-piperidines the electrophile is introduced with trans stereochem.
These reactions are suggested to involve twist boat conformations consistent with an x-ray crystal structure of 2-methyl trimethylstannyl phenyl-N-Boc-piperidine. Boc-pyrrolidine lithiates more rapidly than Boc-piperidine, provides 2-substituted products with electrophiles, and on further lithiation-substitution gives 2,5-cis- and -trans-substituted products. Boc-perhydroazepine provides 2-substituted products by the sequence and on further lithiation-substitution gives 2,7-trans-disubstituted products.djxeeder.com/9336.php
Stereochemical Course of Deprotonation-Acylation of N-Boc- and N - PDF Free Download
A mechanistic rationalization of these results is given that invokes nonbonding interactions between the stabilizing groups and piperidine ring substituents. I gave mixts. The threo isomers were most often in the form of cyclic carbamates III. Hydrolysis gave the N-unsubstituted piperidines. The configuration of most products was consistent with equatorial substitution.
However, several I, e.
The addn. Exclusive conversion to an equatorial threo amino ester III is obsd.