Categories: C-C Bond Formation > Oxygen-containing molecules > Carboxyl derivatives >
Synthesis of α-hydroxy carboxylic derivatives by 1,2-addition
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Recent Literature
An organic photoredox catalysis reaction converts aliphatic carboxylic acids
to transient alkyl radicals
and α-ketocarbonyls to persistent ketyl radicals,
which couple selectively under mild reaction conditions based on
the persistent radical effect. Primary, secondary, and tertiary aliphatic
carboxylic acids can used to introduce various alkyl substituents.
K. Ota, K. Nagao, H. Ohmiya, Org. Lett., 2021, 23,
4420-4425.
A combination of weak Lewis acid (LiCl) and weak Brønsted acid (hexafluoroisopropanol,
HFIP) promotes efficiently the Friedel-Crafts reaction of electron-rich aromatic
compounds with ethyl glyoxylate.
M. Willot, J. Chen, J. Zhu, Synlett, 2009,
577-580.
The asymmetric Friedel-Crafts reaction of N,N-dialkylanilines with
ethyl glyoxylate has been achieved by the catalysis of titanium complexes of
BINOL derivatives to give the corresponding mandelic acid ethyl esters in
high yields (85-99%) and good to excellent enantioselectivity (80-96.6% ee).
Y. Yuan, X. Wang, X. Li, K. Ding, J. Org. Chem.,
2004, 69, 146-149.
Chiral allenes appended with basic functionality can serve as ligands for
transition metals. An allene-containing bisphosphine coordinated to Rh(I)
promotes the asymmetric addition of arylboronic acids to α-keto esters with high
enantioselectivity. Solution and solid-state structural analysis reveals that
one olefin of the allene can coordinate to transition metals, generating bi- and
tridentate ligands.
F. Cai, X. Pu, X. Qi, V. Lynch, A. Radha, J. M. Ready, J. Am. Chem. Soc., 2011,
133, 18066-18069.
Related
The tandem ylide formation/[2,3]-sigmatropic rearrangement between donor/acceptor
rhodium carbenoids and chiral allyl alcohols generates two vicinal stereogenic
centers in a convergent C-C bond forming process. Any of the four possible
stereoisomers can be selectively synthesized by appropriate combination of the
chiral catalyst Rh2(DOSP)4 and the chiral alcohol.
Z. Li, B. T. Parr, H. M. L. Davies, J. Am. Chem. Soc., 2012,
134, 10942-10946.