Three methods have been developed for generating alkynylsamariums: (1) reduction of iodoalkynes with SmI2 in the presence of HMPA, (2) deprotonation at the terminal position of 1-alkynes either by tetrahydrofurylsamarium generated by PhI and SmI2 in THF, or, (3) deprotonation by butyllithium followed by metal-metal exchange with SmI3. Alkynylsamariums arising from iodoalkynes with SmI2? undergo coupling with carbonyl compounds under both Barbier and Grignard conditions in benzene-HMPA or THF-HMPA as a solvent system. Tetrahydrofurylsamarium generated from iodobenzene and SmI2 in THF can deprotonate from terminal alkynes to yield alkynylsamariums whereas other alkylsamariums, such as ethyl-, isopropyl, cyclohexyl-, and cyclopentylsamarium do not work well. Metal-metal exchange between an alkynyllithium and SmI3 is also effective; the reactive species in this case would be alkynylsamariums rather than alkynyllithiums. To reveal the properties of alkynylsamariums, we examined the stability and reactivity of alkynylsamariums toward Various electrophiles. (C) 2000 Elsevier Science Ltd. All rights reserved.
Hydroborations, reductions and reductive iodinations using BHI2: N(C2H5)2Ph Complex
作者:Ch. Kishan Reddy、Mariappan Periasamy
DOI:10.1016/s0040-4020(01)80500-7
日期:1992.1
useful for hydroboration of alkenes, reduction of amides, iodination of alcohols, reductive iodination of carboxylic acids, aldehydes and ketones. Selective hydroboration of monosubstituted olefin over disubstituted olefinic moiety and terminal olefins over internal alkyne moiety have been achieved using this reagent. Carboxylic esters and nitriles are not affected by this reagent. Selective hydroboration
通过BH 3:N(C 2 H 5)2 Ph与I 2反应制备的BHI 2:N(C 2 H 5)2 Ph络合物可以用于烯烃的硼氢化,酰胺的还原,醇的碘化,羧酸,醛和酮的还原碘化。使用该试剂已经实现了在二取代的烯烃部分上的单取代烯烃和在内部炔烃部分上的末端烯烃的选择性氢硼化。羧酸酯和腈不受该试剂的影响。在酯和腈官能团的存在下,实现了1-烯烃的选择性硼氢化和环己酮的选择性还原碘化。
Copper(I) and phase transfer catalyzed allylation of alkynes