Functionalised organotitanium compounds: from lithium to titanium intermediates in chemoselective reactions with carbonyl compounds
作者:Isidro M Pastor、Miguel Yus
DOI:10.1016/s0040-4020(01)00103-x
日期:2001.3
The reaction of functionalised organolithium compounds 1 with an equimolecular mixture of two carbonyl compounds in the presence of 2 equiv. of triisopropoxytitanium chloride can discriminate between aldehyde and ketone, the process being selective for aldehydes at room temperature. Electronic and steric effects have been observed for different aldehydes.
Lithiation Reactions Catalyzed by Linear and Cross-Linked Arene-Based Polymers. Generation of Functionalized Organolithium Compounds
作者:P. Candela、C. Gómez、M. Yus
DOI:10.1023/b:rujo.0000044541.84132.e5
日期:2004.6
Lithiation of various substrates, such as chlorinated acetals, alpha-chloro ether, dichloro derivatives, benzo-fused heterocycles, and allyl and benzyl derivatives, with excess lithium powder in the presence of a catalytic amount of soluble linear or insoluble cross-linked arene (naphthalene or biphenyl)-based polymers yields the expected organolithium intermediates. The latter react with electrophiles either in two steps or under Barbier-type reaction conditions to afford the corresponding adducts. The catalyst is easily recuperated by filtration at the end of the process, and the procedure can be regarded as a reasonable alternative to the use of free arenes as electron carrier in lithiation reactions.
Polyphenylene as an electron transfer catalyst in lithiation processes
作者:Miguel Yus、Cecilia Gómez、Pablo Candela
DOI:10.1016/s0040-4020(02)00620-8
日期:2002.7
The lithiation of different functionalised chlorinated materials (1a-c), dichlorinated compounds (1d-f) and benzofused cyclic ethers (1g,h) with lithium powder in the presence of catalytic amounts of either linear (LPP) or crosslinked (CPP) polyphenylene, in THF at temperatures ranging between -78 and 20degreesC, leads to the expected organolithium intermediates (1a-h), which by reaction with electrophiles [(BuCHO)-C-t, PhCHO, Et2CO, (CH2)(5)CO, PhCOMe, Me3SiCl] gives, after hydrolysis with water, the expected products 2aa-hf. (C) 2002 Elsevier Science Ltd. All rights reserved.