An Improved Protocol for the Preparation of 2,6-DI(<i>tert</i>-Butyl)-4-methylphenyl (BHT) Alkanoates
作者:P. A. Evans、A. L. Stanley
DOI:10.1080/00397919508011385
日期:1995.2
Abstract Treatment of the acid chloride derivatives 2a-e with potassium 2,6-di(tert-butyl)-4-methyl phenoxide 1b afforded the corresponding BHT esters 3a-e in 83–95% yield.
Structures of three lithium ester enolates by x-ray diffraction: derivation of reaction path for cleavage into ketene and alcoholate
作者:Dieter Seebach、Rene Amstutz、Thomas Laube、W. Bernd Schweizer、J. D. Dunitz
DOI:10.1021/ja00305a014
日期:1985.9
Crystal structure analyses have been carried out for lithium enolates of the following three esters: tert-butyl propionate ((Z)-1), tert-butyl2-methylpropionate (2), and methyl 3,3-dimethylbutanoate ((Z)-3). Enolates (Z)-1 and 2 are dimeric (with one TMEDA per Li atom), whereas (2)-3 is tetrameric (with one THF per Li atom). The Z configuration of 1 and 3 established by X-ray analysis is in agreement with
对以下三种酯的烯醇锂进行了晶体结构分析:丙酸叔丁酯 ((Z)-1)、2-甲基丙酸叔丁酯 (2) 和 3,3-二甲基丁酸甲酯 ((Z)-3 )。烯醇化物 (Z)-1 和 2 是二聚体(每个锂原子一个 TMEDA),而 (2)-3 是四聚体(每个锂原子一个 THF)。通过 X 射线分析建立的 1 和 3 的 Z 配置与爱尔兰指定的配置一致。通过对酯烯醇基团几何结构的详细分析,可以推导出此类分子分解的反应路径轨迹。该分析表明乙烯酮作为中间体的含义可以通过化学方法得到证实。尽管酯烯醇化物作为合成有机化学中的反应中间体具有核心重要性,关于所涉及的金属化物种的实际结构知之甚少。这种信息的缺乏主要是由于酯烯醇化物的总体稳定性低。事实上,仅通过 X 射线分析确定了酯的两种金属衍生物的结构:一种是衍生自溴乙酸叔丁酯的 Reformatksy 试剂2,另一种是强酸性五(甲氧基羰基)的锂衍生物。 ) 环戊二烯。3
Acylation and esterification of the aryloxide ligand in [AIMe(dbmp)<sub>2</sub>]. Crystal structures of [AIMe(dbmp)-(bhmap)], Hbhmap and OC(dbmp)Bu<sup>t</sup>(Hdbmp = 2,6-di-tert-butyl-4-methylphenol, Hbhmap = 3-tert-butyl-2-hydroxy-5-methylacetophenone)
作者:Michael B. Power、Simon G. Bott、Elizabeth J. Bishop、Kelli D. Tierce、Jerry L. Atwood、Andrew R. Barron
DOI:10.1039/dt9910000241
日期:——
The reaction of [AlMe(dbmp)2] (Hdbmp = 2,6-di-tert-butyl-4-methylphenol) with O = C(Cl)Me leads to acylation of one of the dbmp ligands and affords [AlMe(dbmp)(bhmap)] 1 (Hbhmap = 3-tert-butyl-2-hydroxy-5-methylacetophenone). Hydrolysis of 1 yields uncomplexed Hbhmap 5. The Et, Pr(i) and Ph analogues of 1 and 5 have been obtained by the use of the appropriate acyl chloride. By contrast, the interaction of [AlMe(dbmp)2] with O = C(Cl)Bu(t) results in the formation of O = C(dbmp)Bu(t) 12 and [AlCl2(dbmp)O = C(Me)Bu(t)}] 13. The molecular structures of 1,5 and 12 have been confirmed by X-ray crystallography.
Regio- and diastereoselective preparation of aldols from .alpha.-branched ketone enolates generated from BHT ester enolates and organolithium reagents. In situ generation and trapping of ketenes from ester enolates
作者:Robert Haener、Thomas Laube、Dieter Seebach
DOI:10.1021/ja00305a013
日期:1985.9
dilute solution), the corresponding silyl enol ethers with trimethylchlorosilane and aldols with aldehydes. The aldols are produced regioselectively and, in the case of unsymmetrical ketenes, diastereoselectively. Almost two dozen examples are described, illustrating the use of BHT ester enolates as nucleophilic ketene precursors. From X-ray crystal structure da t a of ester lithium enolates we could
在烷基锂化合物的存在下,由支链 2,6-二叔丁基-4-甲基苯基 (BHT) 链烷酸酯和 3 至 6 元环羧酸酯衍生的锂烯醇化物的热诱导裂解为烯酮和 LiO-BHT,苄基锂或苯基锂允许产生热力学不稳定的四取代酮烯醇化物。在选择的条件下(无酰胺碱,稀溶液),这些烯醇化物产生相应的甲硅烷基烯醇醚与三甲基氯硅烷和醛醇与醛。醛醇是区域选择性产生的,在不对称烯酮的情况下,非对映选择性产生。描述了近两打例子,说明了 BHT 酯烯醇化物作为亲核烯酮前体的用途。根据酯锂烯醇化物的 X 射线晶体结构数据,我们可以预测离去基团从 sp2 中心开始消除并形成 a 的轨迹(参见图 1 式 A 中的黑色箭头)。我们也可以制作 0002-7863/85/1507-5396$01.50/0