61878-67-9

Upstream product

• 2040-15-5 2',4',6'-trimethylpropiophenone 
• 100-52-7 benzaldehyde 
• 72658-08-3 (Z)-1-(2,4,6-trimethylphenyl)-1-<(trimethylsilyl)oxy>-1-propene 
• 72658-15-2 (E)-1-(2,4,6-trimethylphenyl)-1-<(trimethylsilyl)oxy>-1-propene 
• 72658-08-3 1-(2,4,6-trimethylphenyl)-1-<(trimethylsilyl)oxy>-1-propene 
• 72657-91-1 Lithium; (E)-1-(2,4,6-trimethyl-phenyl)-propen-1-olate 

Relevant academic research and scientific papers

Ytterbium Trifluoromethanesulfonate Mediated Cross-Aldol Reaction between Ketones and Aldehydes

The cross-aldol reaction between a ketone and an aldehyde proceeded smoothly with threo diastereoselection favorably mediated by ytterbium trifluoromethanesulfonate and tertiary amine in diethyl ether or in dichloromethane.A ytterbium enolate was trapped

STEREOCHEMISTRY OF THE FLUORIDE CATALYZED ALDOL REACTION OF ENOL SILYL ETHERS. EVIDENCE FOR ANOTHER NON-CHELATE TRANSITION STATE

Stereochemistry of the tetrabutylammonium fluoride catalyzed aldol reaction of enol silyl ethers was examined for both tri- and tetra-substitued enolates to find that the previous "extended, non-chelate" transition model (A) applicable only for enolates w

Acyclic Stereoselection. 36. Simple Diastereoselection in the Lewis Acid Mediated Reactions of Enol Silanes with Aldehydes

The Lewis acid mediated aldol reactions of enol silanes with aldehydes have been investigated.The effects of enol silane structure, both nature of the ligand at the silyloxy carbon and the geometry of the double bond, the aldehyde structure, and the nature of the Lewis acid have been studied.In general, the reactions of prochiral enol silanes with prochiral aldehydes show little simple diastereoselection (Table I).An exception is Z enol silane 7, derived from ethyl tert-butyl ketone, which shows synthetically useful anti selectivity.Enol silane 36 may therefore be used as an anti-selective propionate equivalent.The chiral α-alkoxy aldehyde 43 shows a high diastereofacial preference in its reactions with enol silanes 42c and 42d provided a Lewis acid capable of expanding its coordination beyond four is used (TiCl4 or SnCl4) (Table II).However, with the related ketene acetal 41b, only modest diastereofacial selectivity is seen (Table II).Aldehyde 43 also shows a high diastereofacial preference, in the chelation-controlled sense, in its reactions with prochiral enol silanes 5-9.However, the simple diastereoselection observed in the latter reactions (Table III) is quite different from that observed in the reactions of prochiral aldehydes with the same enol silanes.For example, enol silane 7, which shows good anti selectivity in its reactions with prochiral aldehydes, gives a 15:1 mixture of the two syn aldols in its reaction with 43; while the reverse is true with the propiophenone-derived enol silanes 8 and 9.Finally, the results obtained in this study, along with those reported by other investigators, have been formulated into a coherent mechanistic rationale involving open transition states of the sort depicted in Figures 1 and 3.

A NEW ALDOL REACTION VIA CERIUM ENOLATES

Cerium enolates formed from cerium (III) chloride and lithium enolates undergo aldol reaction with ketones or sterically crowded aldehydes to afford the corresponding β-hydroxyketones in high yields.

ERYTHRO SELECTIVE ALDOL CONDENSATION USING TITANIUM ENOLATES

Titanium enolates derived from ketones and esters react with aldehydes to afford erythro adducts with high diastereoselection.

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.