One catalyst for two distinct reactions: sequential asymmetric hetero Diels–Alder reaction and diethylzinc addition
作者:Haifeng Du、Xue Zhang、Zheng Wang、Kuiling Ding
DOI:10.1016/j.tet.2005.08.007
日期:2005.10
addition to the benzaldehyde, affording the corresponding secondary alcohol with up to 94.5% ee under optimized conditions. On the basis of these facts, the integration of two distinct enantioselective reactions, HDA and diethylzincaddition reactions, has been realized in one-pot with the promotion of a single chiralzinc catalyst in a sequential manner. The impact of diimine additive on the catalytic system
Enantio- and diastereoselective titanium-TADDOLate catalyzed addition of diethyl and bis(3-buten-1-yl) zinc to aldehydes a full account with preparative details
作者:Dieter Seebach、Albert K. Beck、Beat Schmidt、Yan Ming Wang
DOI:10.1016/s0040-4020(01)89373-x
日期:1994.4
enantioselective addition of alkyl groups from organozinc reagents to aldehydes (19 examples). With 0.05 – 0.20 equiv. of the diisopropoxy-Ti-TADDOLate bearing four 2-naphthyl groups and 1.2 equiv. of Ti(OCHMe2)4 in toluene or ether solution the best results are obtained: ≥ 98 : 2 enantiomer ratios with all types of aldehydes tested (saturated, olefinic, and acetylenic aliphatic, aromatic, and heteroaromatic)
Formation of mixed aryl–, alkyl–lithium aggregates in the heteroatom assisted lithiation of α,α′-dialkyl substituted 1,3-bis[(dimethylamino)methyl]benzene1These results were presented in part at the Symposium `Frontiers in Organometallic Chemistry' at the Spring 1997 American Chemical Society meeting in San Francisco.12Dedicated to Prof. Ken Wade on the occasion of his 65th birthday, thanking him for his `rules', discussions and long friendship.2
作者:Johannes G. Donkervoort、José L. Vicario、Evelien Rijnberg、Johann T.B.H. Jastrzebski、Huub Kooijman、Anthony L. Spek、Gerard van Koten
DOI:10.1016/s0022-328x(97)00554-8
日期:1998.1
The heteroatom assisted lithiation of 1,3-bis[1-(dimethylamino)ethyl]benzene with n-BuLi afforded 2,6-bis[1-(dimethylamino)ethyl]phenyllithium. An X-ray crystal structure determination revealed a dimeric aggregate in which the four benzylic chiral centers are identical, pointing to stereoselective crystallization. In contrast, reaction of 1,3-bis[1-(dimethylamino)propyl]benzene with n-BuLi afforded a dimeric aggregate comprising the parent lithiated compound and n-BuLi in a 1:1 molar ratio. The four Li atoms and the four bridging carbon atoms are arranged in a unique ladder-type C-Li-2-C-2'-Li-2-C framework. (C) 1998 Elsevier Science S.A.