73198-88-6Relevant academic research and scientific papers
Synthesis of Ynolates via Double Deprotonation of Nonbrominated Esters
Sun, Jun,Yoshiiwa, Toshiya,Iwata, Takayuki,Shindo, Mitsuru
supporting information, p. 6585 - 6588 (2019/09/30)
Herein, we report a double deprotonation method used for the preparation of ynolates starting from nonbrominated 2,6-di-tert-butylphenyl esters. The current method is superior to the previously described double lithium/halogen exchange approach because easily accessible starting materials are used. This method will be especially useful for preparation of ynolates bearing functional groups in organic synthesis.
A chiral ligand-mediated asymmetric addition of a lithium BHA ester enolate to an aldehyde
Nomura, Yumiko,Iguchi, Mayu,Doi, Hirohisa,Tomioka, Kiyoshi
, p. 1131 - 1134 (2007/10/03)
The asymmetric reaction of a lithium enolate generated from a BHA (2,6-di-tert-buty-4-methoxyphenyl) propanoate was allowed to react with benzaldehyde in the presence of a diether-type chiral ligand affording the corresponding anti-aldol product in a moderate enantioselectivity. A tetradentate ligand induced better enantioselectivity albeit relative loss of anti-selectivity. A variation of lithiating amide agent affected the selectivity, indicating involvement of an amine as a component of the mixed aggregate. Absolute configuration of some of the aldol products was determined by standard transformations.
ACYCLIC STEREOSELECTION-13; ARYL ESTERS: REAGENTS FOR THREO-ALDOLIZATION
Heathcock, Clayton H.,Pirrung, Michael C.,Montgomery, Stephen H.,Lampe, John
, p. 4087 - 4095 (2007/10/02)
Preformed Li enolates of hindered aryl esters condense with aldehydes to give predominantly threo aldols.The method has been explored with esters 3 (DMP propionate), 4 (BHT propionate), 5 (DBHA propionate).DMP propionate reacts with benzaldehyde and α-unbranched aliphatic aldehydes to give threo:erythro ratios of about 6.5:1.However, with α-branched aliphatic aldehydes, ester 3 gives only threo-aldols.BHT propionate and DBHA propionate give only threo-aldols with all aldehydes studied.The DMP aldols may be converted into β-hydroxy acids by simple hydrolysis with KOH in aqueous methanol.BHT aldols cannot be hydrolyzed without retroaldolization.However, these aldols can be reduced to diastereomerically pure 1,3-diols.The DBHA aldols can converted into β-hydroxy acids by a method involving oxidation with ceric ammonium nitrate (CAN) in aqueous acetonitrile.Threo-selectivity is also seen in the condensations of DMP butyrate (15), DBHA butyrate (16), DMP pentenoate (17), and BHT pentenoate (18).The approach has been utilized in a stereoselective synthesis of racemic methyl corynomycolate.
Acyclic Stereoselection. 8. A New Class of Reagents for the Highly Stereoselective Preparation of threo-2-Alkyl-3-hydroxycarboxylic Acids by the Aldol Condensation
Pirrung, Michael C.,Heathcock, Clayton H.
, p. 1727 - 1728 (2007/10/02)
threo-3-Hydroxy-2-methylcarboxylic acids may be prepared in high stereochemical yield by condensing aryl propionates 1 or 2 with aldehydes followed by hydrolytic or oxidative removal of the aryl group.
