Regioselectively substituted diethyl 3-furylphosphonates have been prepared in good yields (55-90%) under very mild conditions by a simple two-step procedure based on ceric ammonium nitrate-promoted oxidative addition of β-ketophosphonates to vinylic acetates followed by acid catalyzed Pall-Knorr cyclization reactions.
An efficient carbanionic synthesis of the phosphonic dicarbonylated compounds 2 was achieved and used as key intermediates in the synthesis of the phosphonic furans 4 by acid-induced Paal-Knorr cyclization reaction.
Mikolajczyk, M.; Grzejszczak, S.; Midura, W., Phosphorus and Sulfur and the Related Elements, 1983, vol. 18, p. 175 - 178
作者:Mikolajczyk, M.、Grzejszczak, S.、Midura, W.、Zatorski, A.
DOI:——
日期:——
Methylenomycin B: new syntheses based on .beta.- and .gamma.-keto phosphonates and .gamma.-keto phosphine oxides
作者:Marian Mikolajczyk、Andrzej Zatorski
DOI:10.1021/jo00003a051
日期:1991.2
Methylenomycin B has been synthesized from diethyl 2-oxobutanephosphonate (4) in three steps in 39% overall yield. Starting from diethyl 3-oxobutanephosphonate (10) and diphenyl(3-oxobutyl)phosphine oxide (13), methylenomycin B has been obtained in 34% and 27% overall yield, respectively. A characteristic feature of these syntheses of methylenomycin B is that the exo-methylene function is introduced via the Horner-Wittig reaction of formaldehyde (36% aqueous solution) with the corresponding alpha-phosphorylcyclopentenones 6 and 20. The latter were obtained from phosphorylated 1,4-diketones by intramolecular base-catalyzed cyclization. A brief discussion of some mechanistic aspects of the Conant reaction is also given.
MIKOLAJCZYK, MARIAN;ZATORSKI, ANDRZEJ, J. ORG. CHEM., 56,(1991) N, C. 1217-1223