Synthesis of homopropargylic alcohols
A rapid and efficient procedure for the solvent-free synthesis of homoallylic and homopropargyl alcohols has been achieved by zinc-mediated Barbier-type reaction of carbonyl compounds at room temperature.
J.-X. Wang, X. Jia, T. Meng, L. Xin, Synthesis, 2005, 2669-2672.
The commercially available resin Amberlyst A-31 promotes a regio- and chemoselective propargylation of aldehydes using potassium allenyltrifluoroborate. This simple method gives products in short reaction times in high yields and purity at room temperature.
T. R. Couto, J. J. R. Freitas, J. C. R. Freitas, I. H. Cavelcanti, P. H. Menezes, R. A. Oliveira, Synthesis, 2015, 47, 71-78.
A highly enantioselective chiral Brønsted acid catalyzed propargylation of aldehydes with allenylboronate allows a practical conversion of a broad range of substrate covering aryl, polyaryl, heteroaryl, α,β-unsaturated, and aliphatic aldehydes.
L. R. Reddy, Org. Lett., 2012, 14, 1142-1145.
3,3′-Br2-BINOL catalyze the enantioselective asymmetric propargylation of ketones using allenyldioxoborolane as nucleophile, in the absence of solvent, and under microwave irradiation to afford homopropargylic alcohols in good yields and high enantiomeric ratios. Diastereoselective propargylations using chiral racemic allenylboronates result in good diastereoselectivities.
D. S. Barnett, S. E. Schaus, Org. Lett., 2011, 13, 4020-4023.
A propargylation of aldehydes and ketones with allenyl and propargyl boronates is mediated by a catalytic amount of zinc. The propargylation with crystalline and air-stable propargyl diethanolamine boronates was also achieved. A catalytic cycle is proposed, and preliminary mechanistic studies are discussed.
D. R. Fandrick, K. R. Fandrick, J. T. Reeves, Z. Tan, C. S. Johnson, H. Lee, J. J. Song, N. K. Yee, C. H. Senanayake, Org. Lett., 2010, 12, 88-91.
Trapping of β,γ-alkynyl aldehydes, generated in situ by treatment of alkynyloxiranes with a catalytic amount of Sc(OTf)3 or BF3·OEt2, by a variety of allyl nucleophiles affords homopropargylic homoallylic alcohols in good yield and selectivity. Subsequent enyne metathesis gives functionalized vinylcyclopentenols.
L. Wang, M. L. Maddess, M. Lautens, J. Org. Chem., 2007, 72, 1822-1825.