A tandem oxidativecouplingreaction of β-ketoallenes and arenes was developed, which leads to the formation of 2-furylmethylarenes using AuCl3 and phenyliodine diacetate. The AuIII salt catalyzed the cyclization of β-ketoallenes to form a 2-furylmethyl gold intermediate, and the subsequent C–H functionalization of arenes proceeded smoothly. During the oxidativecoupling, nucleophilic additions occurred
quite scarce. We describe an extremely mild and selective method for either the propargylation or allenylation of carbonyl compounds catalyzed by the abundant, safe, and inexpensive metal titanium. These reactions can selectively provide homopropargylic alcohols from aldehydes and ketones or α‐hydroxy‐allenes from aldehydes. The mechanisms involved were also investigated.
Titanium/Palladium-Mediated Regioselective Propargylation of Ketones using Propargylic Carbonates as Pronucleophiles
作者:Alba Millán、Luis Álvarez de Cienfuegos、Ana Martín-Lasanta、Araceli G. Campaña、Juan M. Cuerva
DOI:10.1002/adsc.201000655
日期:2011.1.10
for the synthesis of homopropargylic alcohols usingpropargyliccarbonates as pronucleophiles is reported. The reaction is based on a combination of transition metal (palladium) and radical chemistry (titanium). The reaction takes place with an excellent regioselectivity and tolerates a great degree of substitution of the starting propargyliccarbonate, thus being an interesting tool in the context
obtained by the reaction of 3-bromo-1-butyne (11) with tributylstibine. The corresponding stiborane (13) reacted with aldehyde to give acetylenic alcohol (14) exclusively in good yield, and the diastereoselectivity was moderately in favour of the threo isomer in the presence of MgBr2. All of the reactions had good chemoselectivity for aldehyde.
Efficient Propargylation of Aldehydes and Ketones Catalyzed by Titanocene(III)
作者:José Justicia、Iris Sancho-Sanz、Enrique Álvarez-Manzaneda、J. Enrique Oltra、Juan M. Cuerva
DOI:10.1002/adsc.200900479
日期:2009.10
We describe a novel method for the propargylation of a wide range of aldehydes and ketonescatalyzed by titanocene(III) complexes under mild reaction conditions and compatible with many functional groups. Homopropargylic alcohols are obtained as the sole products even when ketones are used as starting materials, which is unusual in Barbier-type propargylations.