3966-31-2

Upstream product

• 925-90-6 ethylmagnesium bromide 
• 20229-41-8 l-menthyl phenylglyoxylate 
• 97690-13-6 C₂₅H₃₉AlNO^(1-)*Li⁽¹⁺⁾ 
• 97690-13-6 C₂₅H₃₉AlNO^(1-)*Li⁽¹⁺⁾ 
• 57133-41-2 2-Hydroxy-2-phenyl-butyric acid (1R,2S,5R)-2-isopropyl-5-methyl-cyclohexyl ester 
• 2633-75-2 ethylzinc chloride 
• 173031-08-8 <(1R,2R)-2-(4-tert-butylphenoxy)cyclohexan-1-yl> phenylglyoxylate 
• 173031-14-6 <(1R,2R)-2-(4-phenylphenoxy)cyclohexan-1-yl> phenylglyoxylate 
• 219598-68-2 (S)-2-hydroxymethyl-N-((R)-2-hydroxy-2-phenyl)-butanoylpyrrolidine 
• 10467-10-4 ethylmagnesium iodide 
• 89616-49-9 (R)-2-hydroxy-2-phenyl-butyric acid methyl ester 
• 21504-01-8 (R)-2-hydroxy-2-phenylbutanal 
• 1074-12-0 phenylglyoxal hydrate 
• 57133-41-2 (1R,2S,5R)-5-methyl-2-(1-methylethyl)cyclohexyl (2R)-2-hydroxy-2-phenylbutanoate 

Downstream Products

• 114489-04-2 (R)-2-Hydroxy-2-phenyl-butyric acid (1S,7aR)-7-((S)-2-hydroxy-2-phenyl-butyryloxymethyl)-2,3,5,7a-tetrahydro-1H-pyrrolizin-1-yl ester 
• 114489-02-0 9-O-<(R)-2-hydroxy-2-phenylbutyryl>heliotridine 
• 114423-00-6 7-O-<(R)-2-hydroxy-2-phenylbutyryl>heliotridine 
• 114489-03-1 7,9-di-O-<(R)-2-hydroxy-2-phenylbutyryl>heliotridine 
• 1439390-89-2 C₂₈H₃₂N₆O₄S₂ 

Relevant academic research and scientific papers

Addition-Rearrangement of Ketenes with Lithium N- tert-Butanesulfinamides: Enantioselective Synthesis of α,α-Disubstituted α-Hydroxycarboxylic Acid Derivatives

Addition of the lithium salts of chiral N-substituted tert-butanesulfinamides to ketenes and subsequent silylation initiates stereoselective [2,3]-rearrangement, which affords enantioenriched α,α-disubstituted α-sulfenyloxy carboxamides through a reaction

The stereoselective synthesis of 2-aryl-2-hydroxybutanoic acid via menthyl chiral auxiliaries

In the presence of titanium(IV) tetraethoxide ((EtO)4Ti), menthyl arylglyoxylates are prepared by transesterification of ethyl arylglyoxylates and natural (-)-(1R,2S,5R)-menthol. Using menthyl as a chiral auxiliary, the corresponding novel (R)-menthyl 2-aryl-2-hydroxybutanoates are synthesized by the addition of Et2Zn with menthyl arylglyoxylates. The structures of the products are characterized by IR and 1H- and 13C-NMR spectroscopy, mass spectrometry, and elemental analysis. The diastereoselectivities are analyzed by HPLC. The addition reactions are completed with good yields and high diastereoisomeric excess (de up to 95%), and, after hydrolysis, the (R)-2-aryl-2-hydroxybutanoic acids are obtained with high optical purities.

Mechanism and scope of salen bifunctional catalysts in asymmetric aldehyde and α-ketoester alkylation

Metal complexes of C2-symmetric Lewis acid/Lewis base salen ligands provide bifunctional activation resulting in rapid rates in the enantioselective addition of diethylzinc to aldehydes (up to 92% ee). Further experiments probed the reactivity of the individual Lewis acid and Lewis base components of the catalyst and established that both moieties are essential for asymmetric catalysis. These catalysts are also effective in the asymmetric addition of diethylzinc to α-ketoesters. This finding is significant because α-ketoesters alone serve as their own ligands to accelerate racemic 1,2-carbonyl addition of Et2Zn and racemic carbonyl reduction. The latter proceeds via a metalloene pathway, and often accounts for the predominant product. Singular Lewis acid catalysts do not accelerate enantioselective 1,2-addition over these two competing paths. The bifunctional amino salen catalysts, however, rapidly provide enantioenriched 1,2-addition products in excellent yield, complete chemoselectivity, and good enantioselectivity (up to 88% ee). A library of the bifunctional amino salens was synthesized and evaluated in this reaction. The utility of the α-ketoester method has been demonstrated in the synthesis of an opiate antagonist.

Enantioselective synthesis of either enantiomer of α-alkyl-α- hydroxy-α-phenylacetic acids using chiral auxiliaries

The enantioselective synthesis of either enantiomer of α-alkyl- α-hydroxy-α-phenylacetic acids was achieved by using 2-acyloxathianes 1a-c and the mixed acyl-S,O-acetals 7 and 8 as chiral auxiliaries, which can straightforwardly be prepared from (1R)-(-)-myrtenal. This procedure allowed the preparation of the title compounds in >95% enantiomeric excess (ee).

Development of bifunctional salen catalysts: Rapid, chemoselective alkylations of α-ketoesters

Lewis acid-Lewis base salen complexes have been identified as highly efficient catalysts for the addition of dialkylzincs to α-ketoesters. In contrast to aldehydes or ketones, the reaction between diethylzinc and α-ketoesters is significant in the absence of catalyst. In the presence of catalyst, the reaction rate is increased over 100-fold relative to the background. Furthermore, the reduction product, which is a major coproduct with other catalysts, is not observed with these bifunctional salens. As a result, high yields of the addition products can be obtained (57-99%). Both the Lewis acid and Lewis base portions of the catalyst are critical to the reactivity and selectivity. The two separate portions of the catalyst have been shown to function in a cooperative manner. Copyright

Isomannide and isosorbide as new chiral auxiliaries for the stereoselective synthesis of tertiary α-hydroxy acids

Isomannide and isosorbide are selectively protected to provide new chiral auxiliaries suitable for the preparation of enantiopure tertiary α-hydroxy acids. Diastereoselective additions of organozinc reagents on the derived phenylglyoxylates afford the desired α-hydroxy acids with 60-99% ee after saponification. Both absolute configurations of the α-hydroxy acids can be accessed, by adapted choice of either the starting diol or the protecting group.

Asymmetric reactions of α-ketoacid-derived hemiacetals: Stereoselective synthesis of α-hydroxy acids

N-Acylation of prolinol with α-ketoacid chlorides results in concomitant hemiacetalization of the α-keto amide by the prolinol hydroxyl group. (R) or (S) α-hydroxy acids are obtained with good enantiomeric excess by stereodivergent reduction of these hemiacetals. Reaction with Grignard reagents at ambient temperature furnishes (R) α-alkyl mandelic acids with good stereoselectivity.

(1R, 2R)-2-nitroxycyclohexan-1-ol: First example of a cyclohexyl based chiral auxiliary with nitroxy function as diastereoface discriminating group

Application of nitroxy substituent as diastereoface discriminating group in a cyclohexyl based chiral auxiliary has been described.Copyright

New cyclohexyl-based chiral auxiliaries: Enantioselective synthesis of α-hydroxy acids

(1R,2R)-2-(4-tert-butylphenoxy) cyclohexan-1-ol (5) and (1R,2R)-2-(4-phenylphenoxy) cyclohexan-1-ol (6) have been used for the first time as chiral auxiliaries. Addition of alkylzinc chlorides to the corresponding glyoxylates 5a, 6a, after hydrolysis, provided (R)-α-hydroxy acids in high optical purities.

Novel Steroidal Chiral Auxiliaries: Enantioselective Synthesis of Chiral α-Hydroxy Acids

The synthesis is reported of three novel steroidal chiral auxiliaries (4) which were used to generate an α-hydroxy acid in high optical purity (90-98percent ee).