Novel Synthesis of 5,6-Dihydro-4<i>H</i>-thieno[3,2-<i>b</i>]pyrrol-5-ones via the Rhodium(II)-Mediated Wolff Rearrangement of 3-(Thieno-2-yl)-3-oxo-2-diazopropanoates
作者:Dong Joon Lee、Kyongtae Kim、Yung Ja Park
DOI:10.1021/ol016995n
日期:2002.3.1
[GRAPHICS]Treatment of thioaryolketene S,N-acetals 12 with Hg(OAc)(2) followed by addition of 2-diazo-3-trimethylsilyloxy-3-butenoic acid alkyl esters 15 in CH2Cl2 at room temperature gave 3-(3-alkylamino-5-arylthieno-2-yl)-3-oxo-2-diazopropanoates 16 in good yields. Subsequent reactions of 16 with a catalytic amount of Rh-2(OAc)(4).2H(2)O in benzene at reflux afforded a mixture of 5,6-dihydro-4H-thieno[3,2-b]pyrrol-5-ones 18 and the corresponding enols 19 in excellent yields.
Orthoester condensation/C O insertion reaction sequence for the preparation of tetrahydrofurans
作者:Michael A. Calter、Priyantha M. Sugathapala
DOI:10.1016/s0040-4039(98)01987-x
日期:1998.11
paper describes a general procedure for the efficient preparation of highly substituted tetrahydrofurans. The condensation of α-diazo-β-ketoester-derived enolates with orthoesters yields diazoacetals1a-1d. These compounds undergo formal CO insertion reactions in the presence of Rh2(OAc)4 to afford tetrahydrofurylacetals2a-2c. Similar insertion reactions of diazoacetals5a-5d yield bicyclic acetals6a-6d,