Total Synthesis of Polyene Natural Product Dihydroxerulin by Mild Organocatalyzed Dehydrogenation of Alcohols
作者:Hexin Xie、Shilei Zhang、Hao Li、Xinshuai Zhang、Sihan Zhao、Zian Xu、Xixi Song、Xinhong Yu、Wei Wang
DOI:10.1002/chem.201103325
日期:2012.2.20
Polyene synthesis: An efficient approach to the total synthesis of polyene naturalproduct dihydroxrulin (1) is described. A novel, mild, direct organocatalytic IBX‐mediated dehydrogenation process of simple alcohols to enals has been developed, which serves as a key step in the synthesis (see scheme).
Rhodium-Catalyzed Regio-, Diastereo-, and Enantioselective Intermolecular [4+2] Carbocyclization of 4-Alkynals with Electron-Deficient Alkenes
作者:Ken Tanaka、Yuji Hagiwara、Masao Hirano
DOI:10.1002/ejoc.200600383
日期:2006.8
We established that a cationic rhodium(I)/dppf or dppb complexcatalyzes a regio- and diastereoselective intermolecular [4+2] carbocyclization of 5-trimethylsilyl-4-pentynals with electron-deficient alkenes leading to cyclohexanones. We also established that a cationic rhodium(I)/(R,R)-Walphos complexcatalyzes a regio- and enantioselective intermolecular [4+2] carbocyclization of 5-substituted 4-pentynals
The photochemically initiated dehydro-Diels-Alder (PDDA) reaction is an efficient and versatile method for the prepa- ration of biaryls. The ring closure may take place both inter- and in- tramolecularly, of which the intramolecular variant is more productive from the preparative point of view. A variety of linkers can be employed to connect the ynone moiety, which acts as the chromophore, with another
photochemical route to naphthalenes is presented. The [4+2] cycloaddition takes place between 3-arylynones and arylacetylenes, in which these moieties may be located intwo molecules (intermolecular PDDA, 1) or in the same molecule (intramolecular PDDA, 5 and 9). Especially the latter approach is attractive from a preparative point of view and permits a straightforward access to highly functionalized naphthalenes