Categories: C-B Bond Formation > Synthesis of boronic acids and boronates >
Synthesis of allylboronic acids and allylboronates
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Recent Literature
A copper-catalyzed γ-selective and stereospecific substitution reaction of
allylic carbonates with bis(pinacolato)diboron afforded allylboron
compounds. Functionalized allylboronates that have an acetal, ester, or
isolated alkene were prepared. The reaction of optically active allylic
carbonates underwent complete chirality transfer.
H. Ito, C. Kawakami, M. Sawamura, J. Am. Chem. Soc.,
2005,
127, 16034-16035.
Cu(I)-catalyzed enantioselective substitution of readily available allylic
carbonates with bis(pinacolato)diboron afforded various α-chiral allylboronates,
including functionalized allylboronates, with high enantiomeric purity.
H. Ito, S. Ito, Y. Sasaki, K. Matsuura, M. Sawamura, J. Am. Chem. Soc., 2007,
129, 14856-14857.
A new method for the synthesis of substituted 2-acylallylmetal reagents in a
highly regio- and stereoselective fashion involving a three-component
assembly of allenes, acyl chlorides, and bimetallic reagents (B-B, Si-Si,
and Sn-Sn) catalyzed by phosphine-free palladium complexes is described.
F.-Y. Yang, M. Shanmugasundaram, S.-Y. Chuang, P.-J. Ku, M.-Y. Wu, C.-H.
Cheng, J. Am. Chem. Soc.,
2003,
125, 12576-12583.
Palladium-catalyzed coupling reactions of functionalized allylboronic acids
with various iodobenzenes under standard Suzuki-Miyaura coupling conditions
afforded selectively the branched allylic products in high to excellent
yields.
S. Sebelius, V. J. Olsson, O. A. Wallner, K J. Szabó, J. Am. Chem. Soc.,
2006,
128, 8150-8151.
S. Sebelius, V. J. Olsson, O. A. Wallner, K J. Szabó, J. Am. Chem. Soc.,
2006,
128, 8150-8151.
In the presence of a chiral phosphoramidite ligand, the palladium-catalyzed
diboration of allenes can be executed with high enantioselectivity with a range
of aromatic and aliphatic allenes. A mechanism is proposed based on
isotopic-labeling experiments, stereodifferentiating reactions, kinetic analysis,
and computational experiments.
H. E. Burks, S. Liu, J. P. Morken, J. Am. Chem. Soc., 2007,
129, 8766-8773.
Pd-catalyzed diboration of prochiral allenes occurs exclusively at the
internal position and is accelerated in the presence of Lewis basic ligands.
A chiral ligand was employed, and the enantiomeric excess of a variety of
diboration products was found to be in the range of 86-92% ee.
N. F. Pelz, A. R. Woodward, H. E. Burks, J. D. Sieber, J. P. Morken, J. Am. Chem. Soc.,
2004,
126, 16328-16329.
Related:
Pd-catalyzed enantioselective diborations of prochiral allenes followed by allylation reactions with primary imines provide vinyl boronates which may be oxidized to give nonracemic Mannich products. Alternatively, enantiomerically enriched homoallylic amine derivatives may be obtained by protonation and Suzuki cross-coupling of the vinyl boronate.
J. D. Sieber, J. P. Morken, J. Am. Chem. Soc.,
2006,
128, 74-75.
