Studies in iridoid synthesis. Chemoselective transformations of cis-1,2,4,6-tetrahydrophthalic anhydride
作者:Anne T. Stevens、James R. Bull、Kelly Chibale
DOI:10.1039/b716256a
日期:——
cis-1,2,4,6-tetrahydrophthalic anhydride was transformed into the corresponding lactone cis-3a,4,7,7a-tetrahydro-3H-isobenzofuran-1-one, which served as a key precursor for a variety of chemoselective synthetic manipulations. Unsuccessful formylation of an ester intermediate resulted in a (E/Z) mixture of vinyl alcohols which were protected as acetates and as a single p-methoxybenzyl (PMB) ether (E)
(Salen)ruthenium-catalyzed Desymmetrization of<i>meso</i>-Diols (2). Apical Ligand Effect on Enantioselectivity
作者:Hideki Shimizu、Tsutomu Katsuki
DOI:10.1246/cl.2003.480
日期:2003.6
Enantiotopos-selectivity of aerobic oxidation of meso-diols using chiral (nitrosyl)Ru(salen) complexes as catalyst was found to be dependent on the nature of their apical ligand. The oxidation with complex 5 possessing an apical hydroxo ligand as the catalyst showed moderate to good enantioselectivity (up to 80% ee).
使用手性(亚硝酰基)Ru(水杨醛胺)配合物作为催化剂,对内消旋二醇的空气氧化反应的立体选择性发现取决于其顶端配体的性质。利用具有顶端羟基配体的配合物5作为催化剂进行的氧化反应显示出中等至良好的立体选择性(高达80% 的 ee 值)。
Chemoselectivity and Unusual Internal Acetal Formation in the Synthesis of a Glycosidation Precursor
作者:Kelly Chibale、Anne Stevens、James Bull
DOI:10.1055/s-2007-990910
日期:——
Chemoselective deprotection of a tert-butyldimethyl (TBS) silyl ether group in the presence of an acetal moiety within an advanced iridoid precursor using scandium trifluoromethanesulfonate at 25 °C unexpectedly leads to internal acetalformation in high yield (70%). The same reaction at 0 °C resulted in spontaneous lactonisation of the diol intermediate, which was further elaborated to an iridoid