Influence of the Double-Bond Geometry of the Michael Acceptor on Copper-Catalyzed Asymmetric Conjugate Addition

2007 ◽  
Vol 2007 (35) ◽  
pp. 5852-5860 ◽  
Author(s):  
Magali Vuagnoux-d'Augustin ◽  
Alexandre Alexakis
Keyword(s):  
Double Bond ◽  
Conjugate Addition ◽  
Michael Acceptor

A Facile and Stereocontrolled Synthesis of γ-Substituted γ-Fluoroglutamates by Conjugate Addition: Conflicting Effect between Fluorinated Enaminoester and Hinderered Michael Acceptor

2010 ◽  
Vol 75 (22) ◽  
pp. 7596-7604 ◽  
Author(s):  
Emmanuelle Drège ◽  
Anaïs Guillaume ◽  
Nadjia Boukhedimi ◽  
Jérôme Marrot ◽  
Claire Troufflard ◽  
...  
Keyword(s):  
Conjugate Addition ◽  
Stereocontrolled Synthesis ◽  
Michael Acceptor

Synthesis of dehydroindolizidine-type poison-frog alkaloids via Michael-type conjugate addition

2017 ◽  
Vol 41 (7) ◽  
pp. 398-402 ◽  
Author(s):  
De-Jun Zhou ◽  
Xue-Yan Li ◽  
Dong Li ◽  
Zhong-Shuai Guo ◽  
Qin-Ling Zhang ◽  
...  
Keyword(s):  
Double Bond ◽  
Stereoselective Synthesis ◽  
Conjugate Addition ◽  
Poison Frog

A concise stereoselective synthesis of proposed dehydroindolizidine-alkaloids of types 179 and 207E1 was accomplished via Michael-type conjugate addition. A comparison of natural 207E and synthesised compound 207E on GC–FTIR revealed the double bond of natural 207E is most likely at the 7,8-position.

scholarly journals Lewis Acid Promoted Trapping of Chiral Aza-enolates

Synthesis ◽  
2019 ◽  
Vol 51 (05) ◽  
pp. 1253-1262
Author(s):  
Francesco Lanza ◽  
Juana Pérez ◽  
Ravindra Jumde ◽  
Syuzanna Harutyunyan
Keyword(s):  
Lewis Acid ◽  
Conjugate Addition ◽  
Conventional Wisdom ◽  
Grignard Reagents ◽  
One Pot ◽  
Michael Acceptor ◽  
Michael Acceptors ◽  
Reactivity Order

We present a study on sequential conjugate addition of ­Grignard reagents to alkenyl-heteroarenes followed by trapping of the resulting enolates, yielding moderate to good diastereoselectivities. Contrary to conventional wisdom, one-pot conjugate addition/trapping using two reactive Michael acceptors in combination with Grignard reagents can proceed via conjugate addition to the least reactive Michael acceptor. This unusual chemoselectivity is triggered by the presence of a Lewis acid, reverting the usual reactivity order of Michael acceptors.

Stereochemical and Mechanistic Aspects of the Aprotic Conjugate Addition Reactions of the Carbanions of Octenyl Sulfides and Octenyl Thiocarbamates With 4-Tert-Butoxycyclopent-2-Enone in the Presence of Hexamethylphosphoric Triamide

1987 ◽  
Vol 40 (5) ◽  
pp. 937 ◽  
Author(s):  
MR Binns ◽  
RK Haynes
Keyword(s):  
Double Bond ◽  
Chemical Shift ◽  
Sulfur Atom ◽  
Reaction Pathway ◽  
Conjugate Addition ◽  
Addition Reactions ◽  
Coupling Constant ◽  
Hexamethylphosphoric Triamide ◽  
Major Reaction ◽  
Phosphoric Triamide

The carbanions of (E)- and (Z)-1-(pheny1thio)oct-2-ene, (E)-1-(methy1thio)- and 1-(t-butyl- thio )oct-2-ene, N,N-dimethyl S-[(E)-oct-2-enyllthiocarbamate and (E)-oct-2-enyl benzothiazole undergo conjugate addition to 4-t-butoxycyclopent-2-enone in the presence of hexamethyl - phosphoric triamide ( hmpa ) in tetrahydrofuran at -70� to give as predominant products diastereomeric mixtures of syn and anti allylic sulfides arising from reaction through C1 of the octenyl carbanions. Also formed in some cases are small amounts of diastereomeric mixtures of syn and anti vinylic sulfides arising from reaction through C3 of the octenyl carbanions. In the absence of the hmpa, carbonyl addition is the major reaction pathway of the carbanions of each of the (E)- and (Z)- octenyl thiocarbamates. The constitutions and stereostructures of all the products have been established through chemical shift and coupling constant correlations of their IH n.m.r. data obtained at 400 MHz. The relative proportions of the regioisomeric allylic and vinylic sulfides are dependent both upon the nature of the non-allylic substituent attached to the sulfur atom, and the geometry of the double bond in the starting octenyl sulfide. While there is no apparent connection between the electronic properties or sizes of the non-allylic substituent and the diastereomer ratios of the allylic and vinylic sulfides, it is noted that the (2)-(phenylthio) octene delivers an allylic sulfide mixture enriched in the syn isomer. It is concluded that the carbanions are configurationally stable at-70� and that the configurations of the vinylic sulfides reflect the configurations of the carbanions from which they are derived. It is also concluded that the reactions proceed under orbital control, as this best accounts for the formation of the vinylic sulfides and is in accord with the results of STO-3G calculations carried out on a series of sulfur-bearing allylic carbanions . The likely angle of attack of the carbanions on the enone system is briefly discussed in terms of a published model relating to the attack of a simple nucleophile on an electrophilic double bond.

ChemInform Abstract: Expedient Synthesis of 3,4-Dihydroquinazolines via Tandem Addition-Conjugate Addition Cyclization of Carbodiimides Bearing a Michael Acceptor.

ChemInform ◽  
2012 ◽  
Vol 43 (22) ◽  
pp. no-no
Author(s):  
Takao Saito ◽  
Hayato Nakano ◽  
Hidenori Terada ◽  
Noriki Kutsumura ◽  
Takashi Otani
Keyword(s):  
Conjugate Addition ◽  
Michael Acceptor
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