Catalytic iron-mediated ene carbocyclizations: formal [4+4]-ene reactions of triene esters
作者:James M. Takacs、Peter W. Newsome、Cynthia Kuehn、Fusao Takusagawa
DOI:10.1016/s0040-4020(01)87749-8
日期:1990.1
2-Substituted-2,7,9-decatrienoates undergo an iron-catalyzed carbocyclization to yield trans-disubstituted cyclopentanes in moderate-to-good chemical yields. The cyclization products are formally the result of a [4+4]-ene reaction in which cis-propenyl and 2-acroyl functionalities are introduced as appendages to the newly formed cyclopentane ring by the cyclization. Triene ester substrates bearing
Copper-Catalyzed Desaturation of Lactones, Lactams, and Ketones under pH-Neutral Conditions
作者:Ming Chen、Guangbin Dong
DOI:10.1021/jacs.9b07932
日期:2019.9.18
A copper-catalyzed desaturation method is reported, which is suitable for converting lactones, lactams and cyclic ketones to their α,β-unsaturated counterparts. The reaction does not require strong base/acid or sulfur/selenium reagents, and can be carried out through a simple one-step operation. The protocol uses inexpensive catalysts and reagents, exhibits excellent scalability and functional group
报道了一种铜催化的去饱和方法,该方法适用于将内酯、内酰胺和环酮转化为它们的 α,β-不饱和对应物。该反应不需要强碱/酸或硫/硒试剂,可通过简单的一步操作进行。该协议使用廉价的催化剂和试剂,具有出色的可扩展性和官能团耐受性。值得注意的是,叔丁醇是唯一产生的化学计量副产物,并且没有观察到过度氧化。通过对照实验、氘标记、自由基钟、EPR、HRMS 和动力学研究研究了反应机理。获得的数据与涉及可逆α-去质子化的反应途径一致,Cu(II)-OtBu 物种,然后进一步氧化所得的 Cu 烯醇化物。
One-Pot Sequential 1,4- and 1,2-Reductions of α,β-Unsaturated δ-Lactones to the Corresponding δ-Lactols with CuCl and NaBH4 in Methanol
作者:Yasunobu Matsumoto、Masahiro Yonaga
DOI:10.1055/s-0033-1340195
日期:——
An efficient, one-pot method for the highly chemoselective synthesis of δ-lactols fromα,β-unsaturatedδ-lactones using CuCl and NaBH4 in methanol was developed.
An electrophilictrifluoromethylation of ketene silyl acetals (KSAs) by hypervalent iodine reagents 1 and 2 has been developed. The reaction proceeds under very mild conditions in the presence of a catalytic amount of trimethylsilyl bis(trifluoromethanesulfonyl)imide (up to 2.5 mol %) as a Lewis acid providing a direct access to a variety of secondary, tertiary, and quaternaryα-trifluoromethyl esters
Highly Enantioselective Intermolecular Cu(I)-Catalyzed Cyclopropanation of Cyclic Enol Ethers. Asymmetric Total Synthesis of (+)-Quebrachamine
作者:Oliver Temme、Shabbir-Ali Taj、Pher G. Andersson
DOI:10.1021/jo9807417
日期:1998.8.1
structures 34c-h, the reaction was used as a key step in the asymmetric synthesis of (+)-quebrachamine 7, an indole alkaloid of the Aspidosperma family. After acid-induced ring opening of bicyclic compound 34f to lactone 40 followed by LiAlH(4) reduction to the masked aldehyde 41, a reaction with tryptamine gave intermediate 42. This alcohol was efficiently converted into the indole alkaloid (+)-quebrachamine