一直觉得学术交流版缺少气氛，个人认为主要是两个原因，一是大家没有时间发贴，二是看不到感兴趣值得讨论的东西。为了鼓励大家的参与，我决定开设这样一种讨论方式，以文献阅读为基础，提出大家各自感兴趣的话题和热点，不占用太多时间，又能学到东西，还促chem8er的交流。
相信搞科研的肯定是要经常阅读文献的，平时看别人的工作，总会发现有的东西能让你眼前一亮，那么就请多花几分钟，传一张图，评论两句，与大家共享你的感想。

下面是具体的方案（以organic chem为例，其它领域当然也请相关的朋友主持），我每周或每两周（试具体参与情况而定）发表主题贴，大家以跟贴形式发表内容，这样可以把一段时间内的亮点工作集中在一起，便于查阅。同时也鼓励跟贴讨论贴出的文献。



语言：中英文不限
任何你觉得有意义的文献都可以


格式（还是有个标准点的格式，看的方便）：
[title]
[reference] journal, year, volume, pages (时间上以本星期内的发表文献为准，不包括ASAP或者Early View，因为我考虑要避免重复)
[background]背景介绍可以直接引用文章里面的介绍部分，主要是帮助大家理解

正文部分贴上你要介绍的文中主要图表数据，加上你的介绍.
（图片的上传可以申请国内的免费blog，上传图片获取地址）

[hilights]文献工作中的亮点，你的评论。你的评论是很重要的，为什么你觉得这个工作重要或者有意义，告诉大家。


最后上传文献的电子版。

[Title]
Development of More Potent 4-Dimethylaminopyridine Analogues


[Reference]
OL, 2007, 9, 401-404

[Background]

Catalytic amounts of 4-dimethylaminopyridine (DMAP) or 4-pyrrolidinopyridine (PPY) cause enormous rate accelerations in the acylation reactions of amines and, particularly, alcohols with carboxylic acid halides and anhydrides. Such reactivity enhancements are not only confined to acylations but also occur in carbamylation, sulfonylation, phosphorylation, and silylation reactions of alcohols and amines.


In this paper, the authors report the development of general protocols for the synthesis of novel N-substituted bicyclic and tricyclic pyridines which is applied in in the esterification reactions of representative tertiary alcohols with acetic anhydride.

The simplified, but well-accepted mechanism of esterification of an alcohol using DMAP, is illustrated in Scheme 1.



the results of DFT calculations of the enthalpy change associated with the isodesmic acetyl-transfer reaction shown in eq 1 at the B3LYP/6-311+G(d,p)//B3LYP/6-31G(d) level of theory (Table 1).



Based on similar reasoning, They predicted that one or two additional cyclic N-substituents on the meta positions of the pyridine ring, as in 3-6, respectively, would provide an even greater stabilization of the acylpyridinium intermediate
because a m-dimethylamino substituent [óm(NMe2))-0.16] is more electron releasing than an alkyl group [óm(Et) ) -0.07], and the six-membered cyclic scaffold would also force the substituent N lone pair orbital to be parallel to the ð-orbitals of the pyridine ring.

They then developed syntheses of bicyclic diaminopyridines 3 and 4, and tricyclic triaminopyridines 5 and 6.




The effectiveness of DMAP, PPY, and catalysts 2-6 was evaluated by following the esterification of 1-ethynylcyclohexanol (1.0 equiv) with acetic anhydride (2.0 equiv)



The tricyclic triaminopyridines 5 and 6 are substantially more effective than DMAP. They are even slightly more effective than 2, which until now was the best catalyst reported for this reaction.

In addition, they have also conducted studies to compare the relative effectiveness of the most potent catalyst 6.



[Hilights]

世界上不存在完美的事物，化学亦然，科学家只能不断的追求最好的结果，Han的工作虽然不是很复杂，但反映着化学家们追求完美的信念。博大的有机化学虽然历经了这么久的发展，但是不完善的地方太多了，很多反应、试剂都有着这样那样的限制，所以需要发展修补的地方还有很多很多。Han的这篇Paper给大位阻醇的酯化提供了一种温和的条件，为合成化学家们提供了一个新的选择，也许很快就会被用到合成当中。

原文：
http://www.box.net/public/ep3x9ihi8l

感觉现代有机化学的试剂、反应越来越复杂，个人认为简单的才是最好的。同样时间下6催化的转化率远好于DMAP，但适当延长反应时间条件下，DMAP能否达到近完全的转化率呢？如果是，就没必要舍简单，选择复杂。
另外DCC/DMAP的条件大位阻醇的酯化，是否也是个较好的选择。

个人觉得，无机或有机的酸碱催化反应都是上个世纪的事了，现在过渡金属催化才是主流。

有机合成讲的是效率、经济性。。。过度金属催化有其用武之地，但不是万能的，真正简单易行的方法才是有用的

[Title]
Tin-Free and Catalytic Radical Cyclizations


[Reference]
JACS, 2007, 129, 770-771

[Background]

Radical cyclization (eqs 1-3), invaluable for natural product synthesis in the laboratory,1 has not been industrially useful because of its reliance on toxic organotin reagents. Special procedures are required to handle trialkyltin hydrides and the waste they generate, and standard purification techniques often leave toxic levels of tin compounds in the product.2 Methods catalytic in tin have been developed,3 along with tin hydride reagents modified to make their removal easier,4 but the need for alternatives to tin remains.5 Substitutes such as (Me3Si)3SiH,6 (Me3Si)3GeH,7 HGaCl2,8 and HInCl2 9 contain a bond to hydrogen stronger than that in Bu3SnH10 and are therefore likely to be less reactive at H. transfer (eq 1). Furthermore, these methods are stoichiometric in some other heavy element, typically iodine, bromine, selenium, or sulfur, which is abstracted by tin to generate the organic radical species (eq 2).



In this paper, the authors looked at the reaction of various alkenes with CpCr(CO)3H (Table 1),16 which has a Cr-H BDE of 61.5 kcal/mol.



The extent of hydrogenation per H¥ transfer for each alkene measures the ratio of kH2 to ktr1 (eq 6).



The data in Table 1 for compounds 1a and 1b show that only alkenes with a single substituent on the incipient radical center are extensively hydrogenated, implying that a secondary radical is appreciably more receptive to a second H. than a tertiary one.

Then they was enableded to design a diene substrate 4 that can be cyclized by the H. transfer agent CpCr(CO)3H.



The reaction of 4 with a catalytic quantity of CpCr(CO)3H was disappointing,



Presumably, the tertiary C-H bond in 7 is too hindered to permit approach of the metalloradical and H. transfer (ktr3)



The formation of the isomerization product 10 in eq 8 suggested that significant CpCr(CO)3. was present.



carring out the reaction between CpCr(CO)3H and 4 under 30 psi of H2 at 22 °C (eq 11, Table 2). Filtration of the reaction mixture through silica gel gave the cyclization products 9 and the hydrogenation product 6, along with a small amount of the isomerization product 10.



Both diastereomers of 9 are formed.

The diene 13 was made from the alkene 12 in one step



Treatment of diene 13 with CpCr(CO)3H at 50 °C for 10 days afforded the cyclization product 14 exclusively.



[Hilights]

自由基环化反应不是什么新鲜的课题，但是摆脱了锡试剂，使反应更加“绿色”了，但是铬也不是什么环保的东西啊。其它方面，作者的构思很巧妙的，包括氢化反应与自由基反应的结合。虽然提升的空间还很大，但是也算给未来指了一条道路。

原文：
http://www.box.net/public/cnmcc8k8qn

建议在每篇文献前面给出通讯联系人。

[Title]
Gold(I)-Catalyzed 5-endo Hydroxy- and Alkoxycyclization of 1,5- Enynes: Efficient Access to Functionalized Cyclopentenes


[Reference]
Fabien Gagosz*, Angew. Chem. Int. Ed. 2007, 46, 1141 –1144

[Background]

The cyclopentyl unit is found frequently in a wide variety of natural products that exhibit biological activity.[1] As a consequence, the development of practical synthetic routes to form five-membered rings remains of interest. Gold(I) complexes have emerged as efficient and mild catalysts for the activation of alkynes towards addition by a variety of nucleophiles,[2] and their potential has been highlighted by numerous studies related to the conversion of enynes into cycloisomerized products.



In this paper, the authors showed us a new method to construct functionalized 5-membered ring (eq 2).



In a first attempt, the model substrate 10 was treated with various Au catalysts.
Remarkably, the treatment of 10 with the biphenylphosphine-based catalyst 12[12] furnished 11 cleanly and rapidly in 98% yield (Table 1, entry 3). Moreover, the use of a 10:1 mixture of CH2Cl2 and MeOH as the solvent led to an even faster reaction to form the desired product in very high yield (Table 1, entry 4).



Then they began to focus their attention on the variation of substrate, including nucleophiles and aryl-substituted alkynes or trisubstituted alkenes, Vinyl and allyl substituents on the alkyne were also tolerated.



To account for all these observations, a mechanism for the formation of the cyclopentenes is proposed in Scheme 1.



To further highlight the synthetic potential of the cyclopentenes obtained in this study, they took advantage of the pendant alkene functionalities present in compounds 28 and 29 to perform a subsequent ring-closing metathesis reaction. Such bicyclic motifs are found in many terpenes, two examples of which are 46 and 47.



作者提供了一种新的构成5-endo环的方法，用了现在非常流行的金催化剂，基于对他人工作的深刻理解，提出了自己的课题（作者是这么说的，当然应该不完全是这样，机遇与偶然性play important role）如果看原文的话，可以发现这一方法具有比较优秀的底物适用性，尤其是一些在金属催化反应中不太稳定的因素都可以克服，对一个反应来说很不错了。对产物使用RCM衍生，证明了该方法的有用（这也是现在做反应的流行趋势），也不失为一个亮点。

原文：
http://www.box.net/public/p1t9stvkmv

Au催化就有点像有机催化，热的一塌糊涂。

Au属于软金属，容易活化炔键或者是联烯。

Toste有一篇最新的Angew.Chem.Ind. Ed， 2007， 46， 912。说的是通过Au活化联烯经过一个类似Nazarov环化得到Cyclopentadiene结构。