The reactions of diazo compounds with lactones. Part 1. Cyclopropanespiro-β-lactones from diketene: synthesis and reactions
作者:Paul V. Murphy、Timothy J. O’Sullivan、Niall W. A. Geraghty
DOI:10.1039/b001393p
日期:——
The cyclopropanespiro-β-lactones 3, 4 and 12 can be prepared by the metal catalysed, or photochemically promoted decomposition reactions of diazocompounds in the presence of diketene. The thermal reactions of these compounds give a variety of products depending on the nature of the spirolactone; these include a furan 9a, 1,4-dicarbonyl compounds 18aâc and 19b, a pyranone 20b, furanones 21a, 21f and 22a and the enol 16. The boron trifluoride promoted reaction of a mixture of 3b and 4b gives a β-ketoacid. Mechanisms are proposed for the formation of these products. The rearrangment of the cyclopropanespiro-β-lactones to furan-2(5H)-ones and furan-2-(3H)-ones 6â8, 21a, 21f, 22a and 24 is shown to be a general reaction that involves metal catalysis. A mechanism based on formation of a metallocycle by a novel insertion of the metal into the CâO bond of the β-lactone ring is proposed for this rearrangement. This accounts for the observed features of the reaction.
Metal catalysed rearrangement of cyclopropanespiro-β-lactones to 2-furanones
作者:Niall W.A. Geraghty、Paul A. Murphy
DOI:10.1016/s0040-4039(00)73482-4
日期:1994.9
The rearrangement of 5-oxo-4-oxaspiro[2.3]hexanes (cyclopropanespiro-β-lactones) to 2(5H)-furanones and 2(3H)-furanones is shown to be a general reaction which is promoted by metal catalysts. A mechanism is proposed, involving the novel insertion of a metal species into the OCβ bond of the β-lactone ring, which explains the basic features of the reaction, including its regioselectivity.