Homoenolate Equivalents Research Articles

Generation of α-amino acid homoenolate equivalents. Synthesis of 3-substituted prolines.

Deprotonation of the N-protected aminoketene-S,S-acetal (6) and reaction of allylic anion (7) with electrophiles leads to adducts (8) which have been converted to 3-substituted prolines (11). Conformationally constrained variants (11d) and (11e) of aspartic and glutamic acid have been prepared.

Chromium carbene complexes in the synthesis of molecules of biological interest

Abstract

ChemInform Abstract: Oxygenated Allylic Silanes: Useful Homoenolate Equivalents for the Stereoselective C‐Glycosidation of Pyranoside Derivatives.

AbstractStereoselective C‐glycosidation of the 1‐acetyltetrabenzylglucopyranose (I) and the tribenzyl‐1,6‐anhydro‐D‐glucopyranose (V) with the allylic silanes (II) and (VI) as homoenolate equivalents in the presence of boron trifluoride etherate produces the glucopyranoses (III) and (VII) as mixtures of anomers and E/Z‐enol stereoisomers.

Oxygenated allylic silanes: useful homoenolate equivalents for the stereoselective C-glycosidation of pyranoside derivatives

Oxygenated allylic silanes: useful homoenolate equivalents for the stereoselective C-glycosidation of pyranoside derivatives

ChemInform Abstract: Optically Active 2‐Ethenyl‐1,3‐dioxolanones as 3‐Carbon Synthons. Allylnickel Derivatives as Homoenolate Equivalents.

AbstractThe metal‐centered nucleophile (II) reacts with the dioxolanone (I) to yield the Ni complex (III) which upon in situ treatment with the silane (IV) gives the derivative (V).

Optically active 2-ethenyl-1,3-dioxolanones as 3-carbon synthons. Allylnickel derivatives as homoenolate equivalents

Reaction de la cyclohexyl-5 R-2 dioxolanne-1,3one-4 (A; R=vinyl) avec le complexe Ni(COD) 2 puis le chloro trimethyl silane; obtention d'un complexe allyl du nickel qui, par reaction photochimique avec des hydrocarbures halogenes, conduit aux α-alcene-1yloxy cyclohexaneacetates de trimethylsilyle; aldolisation par le dimethylacetal du benzaldehyde en compose A avec R=α-(α-methoxybenzyl) phenethyl

An easy access to β-acyl- and β-aryl-propionaldehydes through a new silylated organotin homoenolate equivalent

Palladium-catalysed cross-coupling of a new umpolung reagent, (α-methoxy-γ-tributylstannyl)allyltrimethyl-silane, with acyl or aryl halides, involves exclusively the vinyl–tin bond and subsequent desilylation with tetrabutylammonium fluoride gives enol ethers, precursors of β-acyl- or β-aryl-propionaldehydes.

Synthetic organic reactions by means of reactive nucleophiles generated through rearrangement of a silyl group

Under basic conditions, 1-(trialkylsilyl)-allylic and -propargylic alcohols have been shown to undergo 1,2-rearrangement of a silyl group from carbon to oxygen to generate the corresponding 3-siloxyallyl and allenyl anionic species. Their synthetic utilities as homoenolate equivalents are described. Furthermore, by using a 3-silyl-4-penten-1-ol system, anionic species have been generated through a similar 1,4-rearrangement of a silyl group and their synthetic use is also discussed.

ChemInform Abstract: Synthesis and Phase‐Transfer Mediated Alkylations of 2‐Diethylamino‐4‐phenylsulfonyl‐2‐butenenitrile. An Efficient Homoenolate Equivalent.

AbstractDiethylacrylamid (I) liefert ein Addukt (IIa), das nach Schwefelung zu (IIb) zu (III) alkyliert und dann substituiert wird.

Synthesis and phase-transfer mediated alkylations of 2-diethylamino-4- phenylsulfonyl-2- butenenitrile an efficient homoenolate equivalent

The title compound is readily prepared from N-diethylacrylamide in three steps. Alkylation of 1 under phase-transfer conditions yields α-cyanoenamines 4 which can be transformed into saturated or unsaturated (α,β or β,γ ) esters.

Stoichiometric generation of magnesium homoenolate equivalents from acyltrimethylsilanes. Synthesis of 1,6-diketone derivatives

Treatment of various acyltrimethylsilanes with vinylmagnesium bromide has allowed a stoichiometric generation of the corresponding 3-(trimethyl-siloxy)allylmagnesiums, which, in the presence of copper(I) trimethylsilyl-acetylide, undergo conjugate addition to several enones to afford the corresponding 1,6-diketone derivatives in good yields.

Rhodium(II) acetate-catalyzed reaction of ethyl 2-diazo-3-oxopent-4-enoates: Simple routes to 4-aryl-2-hydroxy-1-naphthoates and β,β-unsaturated esters. The dianion of ethyl 4-(diethylphosphono)acetoacetate as a propionate homoenolate equivalent

Rhodium(II) acetate-catalyzed decomposition of ethyl 2-diazo-3-oxopent-4-enoates results in the formation of either 4-aryl-2-hydroxy-naphthoates or β,γ-unsaturated esters. In the latter transformation, the dianion of 4-(diethylphosphono)acetoacetate functions as a propionate homoenolate equivalent.

Diastereoselective Homoaldol Reaction with a (1‐Oxycrotyl)aluminum Compound, a Homoenolate Equivalent of n‐Butanal

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1982, 961. DOI:10.1002/anie.198209610

Preparation et reactivite du derive lithie issu du dioxolanne du -ceto pentanoate de trimethylsilyle.

The organolithium reagent 4 issued from trimethylsilyl 4,4-ethylendioxypentanoate 3 reacts with ketones; it affords β-hydroxy-acids 7 and β-ethylenic ketones 8. This reaction is an efficient route for carbonyl olefination. 4 also acts towards mixed carboxylic and carbonic anhydrides as a homoenolate equivalent.

Lithiated Allyl N,N‐Dialkylcarbamates as Homoenolate Equivalents; Synthesis of Protected 4‐Oxoalkanoates

Lithiated Allyl <i>N,N</i>‐Dialkylcarbamates as Homoenolate Equivalents; Synthesis of Protected 4‐Oxoalkanoates

Three carbon annelation reagents: unsaturated alpha aminonitriles as homoenolate equivalents

α-Aminonitriles and (R = Me) can react as either acyl anion or β-homoenolate equivalents on varying the reaction conditions. Both modes of reaction are potentially useful in three carbon annelations.

Chiral homoenolate equivalents. I. Asymmetric synthesis of β-substituted aldehydes via metalated chiral allylamines

Metalated chiral allylamines of type 2 (M = Li, K) are used as chiral homoenolate equivalents and allow after alkylation and acidic hydrolysis asymmetric CC bond formations to β-substituted aldehydes in enantiomeric excesses up to 67%.

β-Diphenylphosphinoyl ketones (Ph2PO·CH2CH2CO·R): stable reagents for β-ketocarbanions

Acetals of the title compounds, available by five different routes, act as homoenolate equivalents by the Horner–Wittig reaction.

Reactions of allylpyrrolidine carbanions with electrophiles. A new homoenolate equivalent

Reactions of allylpyrrolidine carbanions with electrophiles. A new homoenolate equivalent