18482-28-5Relevant articles and documents
Synthesis of allenyl ketones and their palladium-catalyzed cycloisomerization/dimerization: Approaching the limits
Hashmi, A. Stephen K.,Choi, Ji-Hyun,Bats, Jan W.
, p. 342 - 357 (2007/10/03)
The preparation of several new allenyl ketones 1a-j and 1o-q is reported. In the case of allenyl ketones with nucleophilic groups in the side-chain like 1k-m, the material polymerized during the purification procedure; with the dialkyl thioether In the product of a Pummerer isomerization, the acetoxymethyl alkyl thioether, 11 was formed. Depending on the route to 1 sometimes either the acetate adducts 8 and the 1-propynyl ketones 9 or the dipropargyl and propargyl allenyl carbinol 14 and 15 were observed as side-products. Good yields of the sensitive aryl γ-halogen-allenyl ketones 23a and 23b were obtained by a new synthetic route, on the other hand the aryl γ-silylallenyl ketone 23c was readily desilylated. Subjecting the new allenyl ketones to the PdCl2(MeCN)2 catalyst provided the 2-substituted furans 2 and the 2,4-disubstituted furans 3 in most cases. The yields and ratios of these products strongly depended on the nature of the groups being present. With the aryl thioether and the γ-halogen allenyl ketones the palladium-catalyzed reaction failed. Detailed structural information about the new products was provided by the X-ray structure analyses of the p-acetamidophenyl propargyl carbinol 6g and the 2-aryl-4-(1-methyl-3-aryl-3-oxo-propen-1-yl furan 3h. Wiley-VCH Verlag GmbH, 1999.
