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The synthesis of the pentacyclic skeleton of Et-743 and the construction of the five chiral centers thereof.1. The core pentacyclic skeleton of phthalascidin was constructed with L-dopa as the starting material via thirteen steps. First, two basic synthons, the C-1 functionalized tetrahydroisoquinoline compounds 8 and N-protected Z-dopa derivative 9, were prepared from L-dopa. They were coupled via amide bond to form the dipeptide compounds 10, which were the first key intermediates. Then the primary hydroxyl groups were transformed into the corresponding amino aldehydes 11 via Swern oxidation. Followed by the intramolecular Pictet-Spengler cyclization, the pentacyclic compounds 12 were synthesized.

五环骨架的构建及五个正确手性中心的确立：1.1我们以L-多巴为起始原料，经过多步官能团保护和转化合成了基本结构单元8然后和苯丙氨酸衍生物9，通过缩合反应生成酰胺中间体10，经Swern氧化得到醛化合物11，然后再次利用分子内改良的Pictet-Spengler反应一步构建c，d两环，得到五环骨架化合物12，最后，实现了21-位羰基向氰基的转化，得到了C-1位官能化的化合物14，化合物14不但具有和Et-743一致的五环骨架，而且分子中五个手性中心立体构型也与其完全相同：其中，3，位和13，位的手性中心由原料L-多巴带入，而1，位，11，位和21，位手性中心则通过不对称诱导而确立。

The first Section begins from play slick and slily with staccato the first theme that echoes each other, then the variation is repeated.

第一段从圆滑奏与断奏相互呼应的第一主题开始，然后变奏着反复。

First of all, I must admit that this is only my third digital camera, and first digital SLR.

首先，我必须承认，这只是我的第三个数码相机，首先是数码单镜反光。

Recommendations: When you accidentally do not like to install the software, not smart aleck of the hard disk you can see the deletion of the software program, which may cause system "registry" error, thereby affecting the stability of the system, there are some software installation process of anti-Uninsatll not write well, can not be restored after deletion of the original features of the system, it would lead to "the procedure is invalid, close the program" or "reinstall" and other errors; there most of the procedures after the removal of 12 would leave the garbage DLL file, which not only caused by the mast system, but also indirectly affect the system's operating efficiency, the best way is twofold: First, the software is used to find the ask a friend first, and then installed it again; Second, the request of various expert advice online.

建议：当您不小心安装了不喜欢的软件之后，不要自作聪明的把硬盘中你所能看得到的软件程序删除，这可能会造成系统"登录"错误，进而影响系统的稳定性，也有某些软件的反安装程序Uninsatll写得并不好，删除后也不能恢复系统本来的面目，反而会出现"程序执行无效，请关闭程序"或"请重新安装"等错误；还有大部份的程序在删除后也都会留下一二个 DLL 的垃圾程序文件，这不仅造成系统的肥大，还会间接影响系统的运行效率，最好的方法有二：其一，是找用过这套软件的朋友先问一问，然后再去装它；其二，上网请求各路高手指点。

She and the white snow fly the first meet was she goes to the white snow flying family to work the first day, the joke which the white snow flew has injured Du Xiaomei.

她和白雪飞的第一次相遇是她去白雪飞家工作的第一天，白雪飞的玩笑伤害了杜小梅。

But for Nen-NiO and Hen-N2O, the first six Ne or He atoms form the first solvation ring.

构型的确定为进一步振动光谱的研究提供了理论依据。

Most people feel some soreness for the first few days or even the first week of camp.

大多数人都觉得有些疼痛的头几天，甚至一个星期的训练营。

The sound of first man is the sound of no first.

一独立个体的声音是没有力量的。

How to find effective market niche, is a complex skill : First, the study of time and space; First, the region

如何去寻找有效的市场空档，是一个复杂的技巧：一是对时空的研究；一是对地区

This is Yuri Gagarin, the first Russian spaceman, as it has been said, the first man that flew to space.

这是尤里加加林，第一个俄罗斯宇航员，因为它已经说了，其中一人说，飞往太空。

This one mode pays close attention to network credence foundation of the businessman very much.

这一模式非常关注商人的网络信用基础。

Cell morphology of bacterial ghost of Pasteurella multocida was observed by scanning electron microscopy and inactivation ratio was estimated by CFU analysi.

扫描电镜观察多杀性巴氏杆菌细菌幽灵和菌落形成单位评价遗传灭活率。