物理有机

物理有机化学作业

——109宿舍

（阐述下列反应并描述其反应机理：）

Baylis-Hillman Reaction Beckmann Rearrangement Benzoin Condensation

Birch Reduction Bischler-Napieralski Reaction Claisen Condensation

Claisen Rearrangement Curtius Rearrangement (Reaction)

Cannizzaro Oxidation Reduction

Darzens Reaction Dieckmann Condensation Favorskii Reaction Fries Rearrangement Heck Reaction Henry Reaction Mannich Reaction Michael Addition

Nef Reaction Pinacol Rearrangement Reformatsky ReactionRitter Reaction Schmidt Reaction Suzuki Coupling Swern Oxidation Tsuji-Trost Reaction Ullmann Reaction

Vilsmeier Reaction Wittig Reaction

Beckmann重排

肟在酸如硫酸、多聚磷酸以及能产生强酸的五氯化磷、三氯化磷、苯磺酰氯、亚硫酰氯等作用下发生重排，生成相应的取代酰胺，如环己酮肟在硫酸作用下重排生成己内酰胺：

反应机理

在酸作用下，肟首先发生质子化，然后脱去一分子水，同时与羟基处于反位的基团迁移到缺电子的氮原子上，所形成的碳正离子与水反应得到酰胺。

迁移基团如果是手性碳原子，则在迁移前后其构型不变，例如：

反应实例

Baylis-Hillman Reaction Baylis-Hillman反应

反应机理：

A key step is the addition of the amine catalyst to the activated alkene to form a stabilized nucleophilic anion. This in situ-generated nucleophile then adds to the aldehyde. Subsequent elimination of the catalyst leads to the observed products.

一个关键的一步是加入胺活化的催化剂烯烃形成一个稳定的亲核性负离子。这situ-generated nucleophile 然后增加醛。随后导致消灭催化剂观测到的产品。

Other activating nitrogen nucleophiles may be suitable too and DMAP and DBU are superior to DABCO in some cases:

其他激活氮nucleophiles也可以推广深度DMAP和DBU是我们的优势,DABCO在某些情况下:

product of the addition of DBU and methylacrylate

For aryl aldehydes under polar, nonpolar, and protic conditions, it has been determined that the

rate-determining step is second-order in aldehyde and first-order in DABCO and acrylate. On the basis of this reaction rate data, Tyler McQuade recently proposed (J. Org. Chem.2005, 70, 3980. DOI) the following mechanism involving the formation of a hemiacetal intermediate:

为芳香醛在极性的,非极性,protic条件,已经定断出限速步骤是二阶在醛和一阶在DABCO、丙烯酸酯。在此基础上,对反应速率数据,泰勒McQuade最近提出(J。有机2005年12月,70,化学3980。往)以下的形成机理有关hemiacetal中级:

Benzoin Condensation 安息香缩合

The Benzoin Condensation is a coupling reaction between two aldehydes that allows the preparation of α-hydroxyketones. The first methods were only suitable for the conversion of aromatic aldehydes.

这是一种偶联反应安息香凝结在两个醛,允许准备α-hydroxyketones。第一个方法只适用于转换的芳香醛类。

Mechanism of Benzoin Condensation

Addition of the cyanide ion to create a cyanohydrin effects an umpolung of the normal carbonyl charge affinity, and the electrophilic aldehyde carbon becomes nucleophilic after deprotonation: A thiazolium salt may also be used as the catalyst in this reaction (see Stetter Reaction).

增加了氰化物离子创建一个cyanohydrin的影响正常的umpolung羰基费用的亲和力,又electrophilic醛碳离子后成为一个thiazolium亲盐也可以用作该反应的催化剂(见Stetter反应)。

A strong base is now able to deprotonate at the former carbonyl C-atom:

强碱deprotonate现在已经能够在前羰基C-atom: