89902-31-8Relevant academic research and scientific papers
Copper-catalyzed aerobic C-C bond cleavage of lactols with N-hydroxy phthalimide for synthesis of lactones
Tnay, Ya Lin,Chiba, Shunsuke
supporting information, p. 873 - 877 (2015/04/14)
The transformation of cyclic hemiacetals (lactols) into lactones has been achieved by Cu-catalyzed aerobic C-C bond cleavage in the presence of N-hydroxy phthalimide (NHPI). The present process is composed of a multistep sequence including a) formation of exo-cyclic enol ethers by dehydration; b) addition of phthalimide N-oxyl radical to the enol ethers followed by trapping of the resulting C-radicals with molecular oxygen to form peroxy radicals; c) reductive generation of oxy radicals and subsequent β-radical fragmentation to generate lactones.
The reactions of diazo compounds with lactones. Part 1. Cyclopropanespiro-β-lactones from diketene: Synthesis and reactions
Murphy, Paul V.,O'Sullivan, Timothy J.,Geraghty, Niall W.A.
, p. 2109 - 2119 (2007/10/03)
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 18a-c 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 13-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 6-8, 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 C-O 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
Geraghty, Niall W. A.,Murphy, Paul A.
, p. 6737 - 6740 (2007/10/02)
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 O-C(β) bond of the β-lactone ring, which explains the basic features of the reaction, including its regioselectivity.
Reactions of Methylenecyclopropanes, VIII. Palladium(0)-catalysed Preparation of Unsaturated γ-Lactones from Methylenecyclopropane and Carbon Dioxide
Binger, Paul,Weintz, Hans-Joachim
, p. 654 - 665 (2007/10/02)
Triphenylphosphane-palladium(0) compounds catalyse the codimerisation of methylenecyclopropane (1a) with CO2 to give 3-methyl-2-buten-4-olide (3a).The same Pd(0) compounds also catalyse the alkylation of 3a with 1a.Therefore, the formation of cotrimers (4a, 5a), cotetramers (6a - 8a), and copentamers (9a, 10a) can not be avoided.The reaction course depends on several parameters, e. g.Pd:PPh3 ratio, polarity of the solvent, CO2-pressure, and temperature.The preparation of 3a in high yield (80percent) is elaborated on the basis of these results.
