Iodine(III)-Mediated Contraction of 3,4-Dihydropyranones: Access to Polysubstituted γ-Butyrolactones
作者:Robin Dagenais、Tommy Lussier、Claude Y. Legault
DOI:10.1021/acs.orglett.9b01893
日期:2019.7.5
underappreciated strategy to access these compounds. To the best of our knowledge, very few examples of this strategy have been reported, with limited investigation of the influence of stereogenic centers on the starting dihydropyranones. We investigated the iodine(III)-mediated contraction of a representative set of dihydropyranone derivatives. The method gives rapid access to functionalized γ-butyrolactones
It′s the iodine: The intra‐ and intermolecular title reaction is catalyzed by an in situgenerated ammonium (hypo)iodite species. Either H2O2 or tert‐butyl hydroperoxide (TBHP) can be used as an environmentally benign oxidant and a wide range of substrates react to give the corresponding α‐acyloxycarbonyl compounds in good to excellent yields.
它是碘:分子内和分子间标题反应是由原位生成的亚碘铵(次同)催化的。H 2 O 2或叔丁基氢过氧化物(TBHP)都可以用作环境友好的氧化剂,并且多种底物反应生成相应的α-酰氧基羰基化合物,收率良好至优异。
Oxidative rearrangement of 2-alkoxy-3,4-dihydro-2H-pyrans: stereocontrolled synthesis of 4,5-cis-disubstituted tetrahydrofuranones including whisky and cognac lactones and crobarbatic acid
Oxidation of 2-alkoxy-3,4-dihydro-2H-pyrans 3 with dimethyldioxirane or MTO/urea–H2O2 followed by Jones oxidation leads to rearrangement and stereocontrolled formation of 4,5-cis-disubstituted tetrahydrofuranones. The method is applied to the synthesis of the whisky lactone 9, cognac lactone 10 and crobarbatic acid 17.
用二甲基二环氧乙烷或MTO /脲-H 2 O 2氧化2-烷氧基-3,4-二氢-2 H-吡喃3,然后进行琼斯氧化,导致4,5-顺式-二取代的四氢呋喃酮的重排和立体形成。该方法适用于威士忌内酯9,白兰地内酯10和巴巴果酸17的合成。
CATALYTIC CONVERSION OF CELLULOSE TO FUELS AND CHEMICALS USING BORONIC ACIDS
申请人:Raines Ronald
公开号:US20130178617A1
公开(公告)日:2013-07-11
Methods and catalyst compositions for formation of furans from carbohydrates. A carbohydrate substrate is heating in the presence of a 2-substituted phenylboronic acid (or salt or hydrate thereof) and optionally a magnesium or calcium halide salt. The reaction is carried out in a polar aprotic solvent other than an ionic liquid, an ionic liquid or a mixture thereof. Additional of a selected amount of water to the reaction can enhance the yield of furans.
Allene epoxidation: synthesis of functionalized lactones by the DMDO oxidation of allenic acids
作者:Jack K Crandall、Elisa Rambo
DOI:10.1016/s0040-4020(02)00698-1
日期:2002.8
products are formed directly from allene oxides, keto lactones are formed. The corresponding spirodioxide intermediates give lactones with appropriately situated α-hydroxyketone moieties. An understanding of the regiochemistry of the epoxidations and the subsequent cyclizations of the reactiveintermediates is developed, as are methods for the manipulation of the experimental conditions to favor the