72658-16-3

Upstream product

• 39149-80-9 tert-butyl 2-bromopropionate 
• 100-52-7 benzaldehyde 
• 84784-58-7 (E)-[(1-methoxy)-propenyloxy]-tert-butyldimethylsilane 
• 89337-61-1 tert-butyl((1-methoxyprop-1-en-1-yl)oxy)dimethylsilane 
• 26735-95-5 2-methyl-3-hydroxy-3-phenylpropionic acid t-butyl ester 
• 20487-40-5 tert-butyl propionate 
• 1663-39-4 tert-Butyl acrylate 
• 104015-38-5 tert-butyl 2-benzoylpropionate 

Relevant academic research and scientific papers

Stereoselective Thio-Michael/Aldol Tandem Reaction to α,β-Unsaturated Esters

A mixture of lithium thiophenolate, α,β-unsaturated ester, and aldehyde in CH2Cl2 afforded Michael/ aldol tandem adducts, β-hydroxy-α-(1-phenylthioalkyl) esters, in moderate to good yields with a high syn-aldol selectivity. The reaction proceeded effectively when CH2Cl2 or ether was used as a solvent. The countercation of thiolate proved important; lithium cation provided the best results. The stereoselectivity and yield of the adducts greatly depended on the steric size of the ester group. Lithium selenolate, generated in situ by treatment of diphenyldiselenide with methyllithium, brought similar results, whereas alkoxide was too inert for the reaction. Application of the reaction to methacrylate provided a useful method to form a quaternary carbon center on a similar stereoselective level. In the reaction with crotonates, on the other hand, the anti-Michael selectivity dominated over the syn-aldol selectivity. The tandem adduct was useful for the stereoselective preparation of trisubstituted tetrahydrofuran via radical cyclization, whose configuration was found to be 2,3-trans-3,5-trans.

Reductive aldol-type reaction of α,β-unsaturated esters with aldehydes or ketones in the presence of Rh catalyst and Et2Zn

The reaction of RhCl(PPh3)3 with Et2Zn easily generated a rhodium-hydride complex (Rh-H) that added to α,β-unsaturated esters to form rhodium enolate complexes by formal 1,4-reduction. These rhodium enolates gave the corre

Rhenium-catalyzed reaction of carbonyl compounds with ketene silyl acetals

It was found that rhenium complex is an effective catalyst for the reaction of carbonyl compounds with ketene silyl acetals. A wide range of β-silyloxy esters is obtained by the treatment of carbonyl compounds with ketene silyl acetals in the presence of

A mild aldol reaction of aryl aldehydes through palladium-catalyzed hydrosilation of α,β-unsaturated carbonyl compounds with trichlorosilane

A mild aldol reaction of aryl aldehydestook place by using N,N- dimethylacrylamide and trichlorosilane with a catalytic amount of tetrakis(triphenyl-phosphine)palladium. A unique anti selectivity was observed in the reaction.

Enolboration. 6. Dicyclohexyliodoborane, a Versatile Reagent for the Stereoselective Synthesis of Either Z or E Enolates from Representative Esters

A smooth, rapid, quantitative, and highly stereoselective synthesis of either Z or E enolates from representative esters has been achieved with dicyclohexyliodoborane, Chx2BI, in the presence of a suitable tertiary amine, such as triethylamine or N,N-diis

Enantioselective aldol and Michael additions of achiral enolates in the presence of chiral lithium amides and amines

It is now well established that lithium enolates and analogous derivatives generally exist as complex structures held together by noncovalent bonds ('supramolecules'). In particular, Li enolates aggregate to give dimers, tetramers, and higher oligomers, whose metal centers may be complexed by solvent molecules or chelating ligands. In addition, the anionoid part of the enolates may hydrogen-bond to weak acids such as secondary amines. Furthermore, such supramolecules can be product-forming species in synthetic reactions of Li enolates. This paper describes our observations of the temporary incorporation of chiral amines or chiral lithium amides into achiral lithium enolate aggregates (an interaction which is simply broken during aqueous workup!) to give enantiomerically enriched products. In particular, enantioselective aldol and Michael additions between achiral enolates and achiral aldehydes or achiral nitroolefins have been achieved in the presence of several chiral amines (or their lithium amides) derived from (S)-valine or (R,R)-tartaric acid. Finally, this report demonstrates the potential usefulness in asymmetric synthesis of ortho lithiation directed by chiral α-aminoalkoxides.

Stereoselective reduction of 2-methyl-3-oxo esters (or amides) with sodium borohydride catalyzed by manganese (II) chloride or tetrabutylammonium borohydride. A practical preparation of erythro and threo-3-hydroxy-2-methyl esters (or amides)

erythro-3-Hydroxy-2-methylpropionates or erythro-3-hydroxy-2-methylpropionamides were prepared with high stereoselectivity by NaBH4 reduction of the corresponding 2-methyl-3-oxo esters or 2-methyl-3-oxo amides in the presence of a catalytic amount of manganese(II) chloride. On the other hand, reduction of these substrates with n-Bu4NBH4 provided threo-isomers selectively. erythro-Selective reduction of 2-methyl-3-oxo amides with NaBH3CN in 1N HCl-MeOH is also described.

ALDOL DIASTEREOSELECTION VIA ZIRCONIUM ENOLATES. PRODUCT-SELECTIVE, ENOLATE STRUCTURE INDEPENDENT CONDENSATIONS.

Both (E)- and (Z)-zirconium enolates have been shown to undergo selective kinetic aldol condensation to give mainly erythro-β-hydroxy ketones, esters and amides.

Acyclic Stereoselection. 7. Stereoselective Synthesis of 2-Alkyl-3-hydroxy Carbonyl Compounds by Aldol Condensation

The stereochemistry of the aldol condensation of preformed lithium enolates of a variety of ethyl ketones and propionic acid derivatives with aldehydes has been investigated.It is found that certain compounds give completely or nearly completely one diastereomeric enolate and that the stereostructure of the resulting aldol is correlated with the stereostructure of the enolate from which is formed.The observed stereochemistry may be understood in terms of an ordered transition state in which both oxygens are oriented in more or less the same direction.It is shown that the observed stereochemistry is kinetically controlled.In many cases, the initial aldol adduct equilibrates to furnish predominantly a threo isomer.The rate of equilibration varies widely, ranging from very fast at -60 deg C with the propiophenone-benzaldehyde adduct to slow at 25 deg C for the ethyl tert-butyl ketone-benzaldehyde adduct.The equilibration behavior of lithium ketolates is compared with that of zinc ketolates, and some differences are noted.A method for achieving erythro-threo equilibration via a chloral hemiacetal is presented.A new reagent is introduced (trimethylsilyloxy ketone 36) which may be used to stereoselectively homologate an aldehyde to an erythro α-methyl-β-hydroxy acid.As an application of the use of stereoselective aldol condensations in synthesis, (+/-)-ephedrine (48) has been synthesized from benzaldehyde in 71 percent overall yield.