在数码时代的今天．随着人们的要求越来越高，在享受音乐的同时不但在耳朵上作出各种要求，还要满足视觉上的要求。正如今流行的MP3文件，播放过程中也增添了很多可视化效果．聆听起来更加“赏心悦目”。在这些可视化效果中．其中就包...在数码时代的今天．随着人们的要求越来越高，在享受音乐的同时不但在耳朵上作出各种要求，还要满足视觉上的要求。正如今流行的MP3文件，播放过程中也增添了很多可视化效果．聆听起来更加“赏心悦目”。在这些可视化效果中．其中就包含了一项实用功能——同步显示歌词。也许有的朋友听说过在Winamp中实现该功能，那么Windows Media Player中你也尝试过了吗？展开更多
Some Stemona alkaloids belonging to the tuberostemospironine group possess a spirolactone moiety with anti-configuration （C-9/C-9a）. In this paper, we describe two approaches to this structural unity. By using bromi...Some Stemona alkaloids belonging to the tuberostemospironine group possess a spirolactone moiety with anti-configuration （C-9/C-9a）. In this paper, we describe two approaches to this structural unity. By using bromine atom as a traceless directing group, the SmI2-mediated reductive coupling of ketone 6 and fl-bromomethacrylate proceeded with complete anti-diastereoselectivity. In the absence of an a-directing （chelation） group, the one-pot reaction of the ketone derived from alcohol 15 with the organozinc reagent generated from bromomethacrylate af- forded spiro-a-methylene-y-lactone derivative 16 as a single diastereomer. These two highly diastereoselective methods would find application in the synthesis of stemona alkaloids containing anti-configured spiro-lactone/pyr- rolidine moieties. In addition, on the basis of our previous work, the total synthesis of （-）-9-epi-11-demethyl- sessilifoliamide J （11）, and an improved synthesis of （-）-9,11-di-epi-sessilifoliamide J （9） were accomplished.展开更多
Due to the chemoselective dehalogenation by SmI2, the addition of α-halomethylsulfones to carbonyl compounds afforded β-hy-droxysulfones. Those reactions with α-bromomethylsulfones gave the products in moderate to ...Due to the chemoselective dehalogenation by SmI2, the addition of α-halomethylsulfones to carbonyl compounds afforded β-hy-droxysulfones. Those reactions with α-bromomethylsulfones gave the products in moderate to good yields. The SmI2-mediat-ed addition of gem-dihalomethylsulfones to ketones also afforded α-halo-β-hydroxysulfones in moderate yields.展开更多
基金Supported by the National Science Fund for Distinguished Young Investigators the NNSF ofChina (20272048+2 种基金 203900505) the Ministry of Education (Key Project 104201) and the Specialized Research Fundfor the Doctoral Program of Higher Education (20020384004)
文摘在数码时代的今天．随着人们的要求越来越高，在享受音乐的同时不但在耳朵上作出各种要求，还要满足视觉上的要求。正如今流行的MP3文件，播放过程中也增添了很多可视化效果．聆听起来更加“赏心悦目”。在这些可视化效果中．其中就包含了一项实用功能——同步显示歌词。也许有的朋友听说过在Winamp中实现该功能，那么Windows Media Player中你也尝试过了吗？
文摘Some Stemona alkaloids belonging to the tuberostemospironine group possess a spirolactone moiety with anti-configuration （C-9/C-9a）. In this paper, we describe two approaches to this structural unity. By using bromine atom as a traceless directing group, the SmI2-mediated reductive coupling of ketone 6 and fl-bromomethacrylate proceeded with complete anti-diastereoselectivity. In the absence of an a-directing （chelation） group, the one-pot reaction of the ketone derived from alcohol 15 with the organozinc reagent generated from bromomethacrylate af- forded spiro-a-methylene-y-lactone derivative 16 as a single diastereomer. These two highly diastereoselective methods would find application in the synthesis of stemona alkaloids containing anti-configured spiro-lactone/pyr- rolidine moieties. In addition, on the basis of our previous work, the total synthesis of （-）-9-epi-11-demethyl- sessilifoliamide J （11）, and an improved synthesis of （-）-9,11-di-epi-sessilifoliamide J （9） were accomplished.
基金Project supported by the National Natural Science Foundation of China （No. 20272040）, the State Key Laboratory of 0rganometallic Chemistry, Shanghai Institute of 0rganic Chemistry, Chinese Academy of Sciences and the Key Laboratory of 0rganic Synthesis of Jiangsu Province.
基金Project supported by the National Natural Science Foundation of China(No.20272050).
文摘Due to the chemoselective dehalogenation by SmI2, the addition of α-halomethylsulfones to carbonyl compounds afforded β-hy-droxysulfones. Those reactions with α-bromomethylsulfones gave the products in moderate to good yields. The SmI2-mediat-ed addition of gem-dihalomethylsulfones to ketones also afforded α-halo-β-hydroxysulfones in moderate yields.
