Titanium Alkoxide Complex of Functionalized Conjugated Dienes. A Versatile Bis-anionic Template for Stereoselective Construction of Carbon Frameworks
作者:Hirokazu Urabe、Kazuhisa Mitsui、Shinya Ohta、Fumie Sato
DOI:10.1021/ja0341844
日期:2003.5.1
Ti(O-i-Pr)4/2i-PrMgCl, to generate diene-titanium alkoxide complexes, the presence of which was verified by hydrolysis and deuteriolysis to give the corresponding monoolefins or their bis-deuterated counterpart. These diene complexes underwent successive addition to an aldehyde (as the first electrophile) and iodine (as the second one) in a highly regio- and stereoselective manner to give the corresponding iodo alcohol
用钛 (II) 醇盐试剂 Ti(Oi-Pr)4/2i-PrMgCl 处理 1,3-丁二烯-2-羧酸盐,生成二烯-钛醇盐配合物,通过水解和氘分解验证其存在得到相应的单烯烃或它们的双氘化对应物。这些二烯配合物以高度区域选择性和立体选择性的方式连续加入醛(作为第一个亲电子试剂)和碘(作为第二个亲电子试剂),得到相应的碘醇。光学活性的 1,3-丁二烯-2-羧酸盐提供了相同的高不对称诱导加合物。除了这些缺电子的二烯外,富电子的2-甲硅烷氧基-1,3-丁二烯也参与了钛络合物的形成,
Iron-catalyzed 1,6-addition of aryl Grignard reagents to 2,4-dienoates and -dienamides
作者:Kohki Fukuhara、Hirokazu Urabe
DOI:10.1016/j.tetlet.2004.11.131
日期:2005.1
1,6-Addition of aryl Grignardreagents to 2,4-dienoates or -dienamides was nicely catalyzed by iron salt to give 5-aryl-3-enoates or the corresponding amides in a highly regio- and stereoselective manner.
A Facile Preparation of <i>e</i><i>xo</i>-Cyclic Conjugated Dienes Fused to Lactams or Lactones via Intramolecular Coupling of Acetylenes and Their Behavior in Diels−Alder Reactions
作者:Hirokazu Urabe、Ryota Nakajima、Fumie Sato
DOI:10.1021/ol0065221
日期:2000.11.1
[reaction: see text] Treatment of bis-acetylenic amides or esters 3 with (eta(2)-propene)Ti(O-i-Pr)(2) generates functionalized titanacyclopentadienes which, upon hydrolytic workup, give exo, exo-cyclic conjugated dienes 4 in good yields. Someregio- and stereochemicalaspects of their Diels-Alderreaction with dienophiles are also disclosed.