查询词典 ketene

Ketenes, notably dimethyl ketene, readily undergo oligomerization and polymerization

烯酮，特别是二甲基烯酮，很容易齐聚和聚合。

These results were different from the observation in the reaction of Cp2LnNPr2 and PhEtCCO,indicating that ligand, steric effect, electronic effect and solvents have an important effect on the insertion of a ketene into the Ln-N bond.

与phEtCCO不同的是，phZCCO偶联插入LoN键形成的新配体不发生1，5一H迁移的异构化反应，可以直接分离得到苯环参与共扼加成反应的中间体CpZLn〔oe(e6HSCphCON'p几)CphZLn-Er(11，孔(12)，Y(13)。

No reactions were observed for reactions of benzodiazepines with ketene atroom temperature; but the reaction of benzothiazepines with monochloroketene gave[2+2] cycloadducts .

发现在室温下苯甲酰基苯并二氮杂卓与烯酮没有反应，而苯并硫氮杂卓与一氯烯酮形成了正常的β-内酰胺环产物。

But the ring fragmentation of 1, 3-dithiolancycolpentyl moiety of ketene-acetals was rarely reported.

然而，对其中的环烷硫基部分——1， 3-二硫戊环的研究甚少。

By the reactions ofα-acylamino ketene--acetals and oxalyl chloride, a serie of pyrrolidinetriones were prepared.

通过α-酰胺基二硫缩烯酮和草酰氯的反应，成功制备了一系列吡咯烷酮类化合物。

In addition,α-alkenoyl ketene--acetals mainly used as the synthons of 3C and 5C, theα-functionalized reactions of which just limited on some simple reactions, as bromination, nitration, acetylation. However, the understanding of the forming of C-C bond atα-position is far from enough.

另外，对于α-烯酰基二硫缩烯酮的研究则主要集中在其作为3C或5C合成子的研究上，其α-位的官能化研究只是停留在溴化、硝化、脱羧等简单的反应之上，而对α-位C-C键的形成还缺乏足够的认识。

Starting with two reactive methylene compounds, ethyl cyanoacetate and malononitrile, two 5-amino-1H-pyrazoles were prepared through the intermediates ketene dithioacetal.

从两个活泼亚甲基化合物开始，经过乙烯酮二硫代缩醛中间体，合成了两个5-氨基-1H-吡唑，以这个两个化合物为中间体，与芳香族和脂肪族α-溴代酮反应，而后经酸催化亚胺化互变异构后得到含咪唑并[1，2-b]吡唑甲硫醚类化合物6a-6g。

Generally, these compounds are derived from accessible α–oxoketen dithioacetals and the common methods of preparation involve regioselective sodium borohydride 1,2-reduce of α–oxoketen dithioacetals, 1,2-nucleophilic addition of organomatals such as organomagnesium, organolithium, Reformatsky regent to α–oxoketen dithioacetals, Baylis-Hillman reaction between polarized ketene dithioacetals and aldehydes.

主要方法包括：使用硼氢化钠1，2-选择性还原α-羰基二硫缩烯酮；利用有机金属化合物（如有机镁试剂，有机锂试剂，Reformatsky试剂等）对α-羰基二硫缩烯酮进行1，2-亲核加成；通过α-羰基二硫缩烯酮与芳醛进行Baylis-Hillman反应等获得。

The intermediate 5-amino-1H-pyrazole-4-carboxylic acid ethyl ester prepared in the first part underwent successively hydrazinolysis, condensations with ketene dithioacetals and alkylations to give rise to the dipyrazolyhnethanes.

从第一部分中的中间体5-氨基-1H-吡唑-4-羧酸乙酯开始，经过肼解、与乙烯酮二硫代缩醛的缩合反应和烷基化反应，合成了二吡唑基甲酮类化合物。

The split between the two groups can hardly be papered over.

这两个团体间的分歧难以掩饰。

This approach not only encourages a greater number of responses, but minimizes the likelihood of stale groupthink.

这种做法不仅鼓励了更多的反应，而且减少跟风的可能性。