General Route to 4a-Methylhydrofluorene Diterpenoids: Total Syntheses of (±)-Taiwaniaquinones D and H, (±)-Taiwaniaquinol B, (±)-Dichroanal B, and (±)-Dichroanone
作者:Mainak Banerjee、Ranjan Mukhopadhyay、Basudeb Achari、Asish Kr. Banerjee
DOI:10.1021/jo052589w
日期:2006.3.31
A general and convergent route for the synthesis of the 4a-methylhydrofluorene diterpenoids has been established through a common hexahydrofluorenoneintermediate (10) obtained via Pd(0)-catalyzed reductive cyclization of a substituted 2-(2-bromobenzyl) methylene cyclohexane (13). The strategy has been successfully utilized for the synthesis of (±)-taiwaniaquinones D (3) and H (5), (±)-taiwaniaquinol
A very expedient and efficient new route toward taiwaniaquinoids, bearing the 4a-methyltetrahydrofluorene skeleton, is reported. Key steps are the intramolecular Friedel−Crafts alkylation of an aryldiene and the degradative oxidation of a methylenedioxy group; the latter process could also be utilized for building the 2-hydroxy-1,4-benzoquinone unit, which is frequently found in natural products. Utilizing
作者:Bara Singh、Siddheshwar K. Bankar、Ketan Kumar、S. S. V. Ramasastry
DOI:10.1039/d0sc01932a
日期:——
A palladium-catalysed intramolecular allylic (hetero)arylation strategy for the synthesis of fused cyclopentenes incorporated with all-carbon quaternary and spiro centres is described. The method is straightforward, shows broad scope, proceeds in synthetically useful yields, and provides a rare means to construct complex cyclopentanoids. The reaction is believed to involve a kinetically unfavourable
Protecting-Group-Free Synthesis of Taiwaniaquinone H Using a One-Pot Thermal Ring Expansion/4π-Electrocyclization Strategy
作者:Xiuxiang Yan、Xiangdong Hu
DOI:10.1021/jo5008652
日期:2014.6.6
A strategy to the 6-5-6 tricyclic scaffold of taiwaniaquinoids was established on the basis of a one-pot thermal ring expansion/4 pi-electrocyclization process. The efficiency of this methodology has been demonstrated through its application in the total synthesis of taiwaniaquinone H, which has been accomplished in three steps and 14% overall yield in a protecting-group-free manner starting from commercially available materials.