Exploration of the diastereoselectivity in an unusual Grignard reaction and its application towards the synthesis of styryl lactones 7-epi-(+)-goniodiol and 8-epi-(−)-goniodiol

RSC Advances ◽  
2016 ◽  
Vol 6 (56) ◽  
pp. 50721-50725 ◽  
Author(s):  
Subhash P. Chavan ◽  
Harshali S. Khatod ◽  
Tamal Das ◽  
Kumar Vanka
Keyword(s):  
Grignard Reagents ◽  
Grignard Reaction ◽  
Styryl Lactones

An unusual diastereoselective Grignard reaction has been explored, where the Grignard reagents are derived from 1,n-dihaloalkanes.

Absolute stereochemistry of (−)-camoensine and (−)-camoensidine in Maackia species

1994 ◽  
Vol 72 (1) ◽  
pp. 214-217 ◽  
Author(s):  
Hajime Kubo ◽  
Shigeru Ohmiya ◽  
Isamu Murakoshi
Keyword(s):  
Grignard Reagents ◽  
Grignard Reaction ◽  
The Absolute ◽  
Absolute Stereochemistry

It was demonstrated that the attack of Grignard reagents such as methyl-, allyl-, and 3,3-dimethoxypropyl magnesium bromides on 11,12-dehydrocytisine occurs on the α-face, to give the corresponding 11α-alkylcytisine. (−)-Camoensine and (−)-camoensidine were synthesized from (−)-cytisine via the Grignard reaction. The absolute stereochemistry of the above alkaloids was confirmed to be 7R, 9R, 11R and 6S, 7R, 9R, 11R, respectively.

scholarly journals Grignard reaction and products. V. Reduction of ketoximes to aziridines with Grignard reagents.

1976 ◽  
Vol 24 (5) ◽  
pp. 1083-1089 ◽  
Author(s):  
KIYOSHI IMAI ◽  
YUICHI KAWAZOE ◽  
TANEZO TAGUCHI
Keyword(s):  
Grignard Reagents ◽  
Grignard Reaction

scholarly journals A versatile method for the N, N-dialkylation of aromatic amines via Grignard reactions on N,N-bis(benzotriazolylmethyl)arylamines

1990 ◽  
Vol 68 (3) ◽  
pp. 456-463 ◽  
Author(s):  
Alan R. Katritzky ◽  
Stanislaw Rachwal ◽  
Jing Wu
Keyword(s):  
Alkyl Group ◽  
Aromatic Amines ◽  
Grignard Reagents ◽  
Grignard Reaction ◽  
Aryl Ring ◽  
Alkyl Groups ◽  
Grignard Reactions ◽  
Stepwise Procedure ◽  
High Yields

Grignard reactions of N,N-bis(benzotriazolylmethyl)arylamines afford the corresponding N,N-dialkylarylamines in high yields. Electron-releasing substituents on the aryl ring facilitate the reaction. Arylamines are N,N-dialkylated with two different alkyl groups by a stepwise procedure: N-benzotriazolylmethylation of an amine followed by a Grignard reaction to introduce the first alkyl group, and repetition of the same procedure to introduce the second alkyl group. Grignard reagents derived from 1,4-dihalobutane, upon reaction with N,N-bis(benzotriazolylmethyl)arylamines, give the corresponding N-aryl-hexahydroazepines together with acyclic products. Keywords: azepine, tertiary arylamines.

scholarly journals Reduction of Bromo- and Iodo-2,6-bis(diphenylphosphanylmethyl)benzene with Magnesium and Calcium

2016 ◽  
Author(s):  
Alexander Koch ◽  
Sven Krieck ◽  
Helmar Görls ◽  
Matthias Westerhausen
Keyword(s):  
Degradation Products ◽  
Grignard Reagents ◽  
Grignard Reaction ◽  
Ether Cleavage ◽  
Degradation Processes ◽  
Coordination Sites ◽  
Subsequent Degradation

Arylmagnesium and -calcium reagents are easily accessible, however, ether degradation processes limit the storability especially of the calcium-based heavy Grignard reagents. Ortho-bound substituents with phosphanyl donor sites usually block available coordination sites and stabilize such complexes. The reaction of bromo-2,6-bis(diphenylphosphanylmethyl)benzene (1a) with magnesium in tetrahydrofuran yields [Mg{C6H3-2,6-(CH2PPh2)2}2] (2) after recrystallization from 1,2-dimethoxyethane. However, the similarly performed reduction of bromo- (1a) and iodo-2,6-bis(diphenylphosphanylmethyl)benzene (1b) with calcium leads to ether cleavage and subsequent degradation products. α-Deprotonation of THF yields 1,3-bis(diphenylphosphanylmethyl)benzene. Furthermore, the insoluble THF adducts of dimeric calcium diphenylphosphinate halides, [(thf)3Ca(X)(µ-O2PPh2)]2 [X = Br (3a), I (3b)], precipitate verifying ether decomposition and cleavage of P-C bonds. Ether adducts of calcium halides [such as [(dme)2(thf)CaBr2] (4)] form supporting the initial Grignard reaction and a subsequent Schlenk-type dismutation reaction.

Stereospecific Grignard reactions of cholesteryl 1-alkenesulfinate esters: Application of the Andersen Protocol to the preparation of non-racemic α,β-unsaturated sulfoxides

2003 ◽  
Vol 81 (6) ◽  
pp. 423-430 ◽  
Author(s):  
Rick R Strickler ◽  
John M Motto ◽  
Craig C Humber ◽  
Adrian L Schwan
Keyword(s):  
Ester Group ◽  
Grignard Reagents ◽  
Grignard Reaction ◽  
Substitution Reactions ◽  
Reaction Conditions ◽  
Enantiomerically Pure ◽  
Sulfinate Esters ◽  
Grignard Reactions

Enantiomerically enriched α,β-unsaturated sulfinate esters of (–)-cholesterol undergo stereospecific substitutions at sulfur when treated in benzene at 6°C with Grignard reagents. Sulfoxides with ees of 85–99.5% are obtained when enantiopure sulfinates are used. The substitution reactions proceed with inversion of sulfur configuration. Enantiomerically pure cholesteryl (E)-2-carbomethoxyethenesulfinate is not a suitable reactant under the Grignard reaction conditions. It is suggested that the ester group induces unwanted reactions significantly lowering both the yield and sulfur stereogenicity.Key words: sulfinate, sulfoxide, Grignard reagents, stereospecific, unsaturated.

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