A new route to 2-alkenyl-1,3-dicarbonyl compounds, intermediates in the synthesis of dihydrofurans
摘要:
A two step synthetic strategy for obtaining 2-alkenyl-1,3-dicarbonyl compounds from the corresponding 1,3-dicarbonyl compounds is reported. The method is based on a Knoevenagel condensation and a Michael addition using a high order organocuprate procedure, and proves to be of general value, Obtained compounds are useful starting materials for the synthesis of furan derivatives, (C) 2002 Elsevier Science Ltd. All rights reserved.
Reactions of 5-aminoisoxazoles with α,β-unsaturated ketones in t-butanol on heating afforded 4,7-dihydroisoxazolo [5,4-b]pyridines. However, when the reactions were carried out at 20° using ethylene glycol as the solvent, the kinetically controlled amino adducts were obtained in excellent yields. The amino adducts were converted into the thermodynamically controlled 4,7-dihydroisoxazolo[5,4-b]pyridines
Novel photochemical rearrangements of dihydro-1,3-thiazines
作者:Shameem H. Bhatia、David M. Buckley、Richard W. McCabe、Anthony Avent、Robert G. Brown、Peter B. Hitchcock
DOI:10.1039/a705331b
日期:——
The 4-methyl compound rearranges to a thiazolidine, which co-exists as an imino-tautomer in solution. The 4-ethyl derivative gives essentially a single isomer of an acyclic thioamido-diene, whilst the 4-benzyl derivative gives a mixture of all four possible thioamido-dienes. The 4-phenyl derivative gave a skeletally rearranged 2,5-dihydro-6H-1,3-thiazine which slowly rearranged to the corresponding
合成了一系列的4-烷基或4-苯基取代的2,3-二氢-6 H -1,3-噻嗪-5-羧酸酯,并在甲苯中光解。4-甲基化合物重排为噻唑烷,噻唑烷在溶液中以亚氨基互变异构体形式共存。4-乙基衍生物基本上给出了无环硫代酰胺基-二烯的单一异构体,而4-苄基衍生物给出了所有四种可能的硫代酰胺基-二烯的混合物。4-苯基衍生物产生骨架重排的2,5-二氢-6 H -1,3-噻嗪,其缓慢重排为相应的2,3-二氢-6 H -1,3-噻嗪。
Cycloaddition of Cross-Conjugated Trienes to Halogenated Quinones
作者:Michel Couturier、Paul Brassard
DOI:10.1055/s-1994-25553
日期:——
The chemoselectivity of [4 + 2] cycloadditions involving electronrich cross-conjugated trienes and halogenated quinones has been examined. The approach provides improved preparations of 6-acetyl-2,3,7-trihydroxyjuglone, solorinic and norsolorinic acids, and averythrin. It also confirms the structure proposed for haematommone and 3,8-dihydroxy-4-methoxy-2-methoxycarbonyl-1-methyl-anthraquinone but invalidates that of sopheranin.
A one step synthesis of previously unknown aminothiopyrandicarboxylates from readily available starting materials is described. The yields range from 33–74%.