An enantioselective intramolecular oxidative cyclization of 4-alkenoic acids was developed. The reaction proceeded via a π-allyl Pd intermediate generated by an allylic C–H activation to give γ-lactone derivatives with moderate to good enantioselectivity. Spiro bis(isoxazoline) ligand, SPRIX, was indispensable for this asymmetric transformation.
Catalytic Dehydrative Lactonization of Allylic Alcohols
作者:Ji Liu、Romain J. Miotto、Julien Segard、Ashley M. Erb、Aaron Aponick
DOI:10.1021/acs.orglett.8b01063
日期:2018.5.18
the synthesis of phthalides and γ-butyrolactones is reported. The method utilizes readily prepared allylic alcohols in formal Au(I)- and Pd(II)-catalyzed SN2′ reactions. Using these catalysts, exclusive formation of the desired five-membered lactones is observed, completely avoiding the competing direct lactonization pathway that forms the undesired seven-membered ring with protic acids and alternative
报道了合成邻苯二甲酸盐和γ-丁内酯的简便策略。该方法在正式的Au(I)和Pd(II)催化的S N 2'反应中利用易于制备的烯丙醇。使用这些催化剂,观察到所需五元内酯的排他形成,完全避免了竞争的直接内酯化途径,后者与质子酸和其他金属盐形成了不希望的七元环。这种温和且操作简单的方法尤其可以耐受环乙亚甲基,应在邻苯二甲酸酯和萜烯合成中找到用途。
Gold(I)-catalyzed synthesis of γ-vinylbutyrolactones by intramolecular oxaallylic alkylation with alcohols
Gold(I)-N-heterocyclic carbene (NHC) complexes proved to be a reliable catalytic system for the direct synthesis of functionalized gamma-vinylbutyrolactones by intramolecular oxaallylic alkylation with primary alcohols. Good isolated chemical yields were obtained for a range of malonyl and acetate derivatives. The good performance in reagent-grade solvents and the functional group/moisture tolerance
Gold Functionalized Platinum M<sub>12</sub>L<sub>24</sub>-Nanospheres and Their Application in Cyclization Reactions
作者:Stefan H. A. M. Leenders、Maximillian Dürr、Ivana Ivanović-Burmazović、Joost N. H. Reek
DOI:10.1002/adsc.201600071
日期:2016.4.28
blocks with a palladium or platinum precursor. These spheres can be functionalized on the inside with a gold(I) chloride complex leading to a high local concentration of gold(I) complexes. The high local concentration makes the neutral gold species an active catalyst. Furthermore, the platinum‐gold spheres can be post‐modified with a silver(I) salt to form cationic gold(I) catalysts. The platinum assemblies
Asymmetric Gold-Catalyzed Lactonizations in Water at Room Temperature
作者:Sachin Handa、Daniel J. Lippincott、Donald H. Aue、Bruce H. Lipshutz
DOI:10.1002/anie.201404729
日期:2014.9.26
Asymmetric gold‐catalyzed hydrocarboxylations are reported that show broad substrate scope. The hydrophobic effect associated with in situ‐formed aqueous nanomicelles gives good to excellent ee’s of product lactones. In‐flask product isolation, along with the recycling of the catalyst and the reaction medium, are combined to arrive at an especially environmentally friendly process.