Diastereoselective Synthesis of γ- and δ-Lactams from Imines and Sulfone-Substituted Anhydrides
摘要:
Sulfone-substituted gamma- and delta-lactams have been prepared in a single step with high diastereoselectivity. Sulfonylglutaric anhydrides produce intermediates that readily decarboxylate to provide delta-lactams with high diastereoselectivity. Substituents at the 3- or 4-position of the glutaric anhydride induce high levels of stereocontrol. Sulfonylsuccinic anhydrides produce intermediate carboxylic acids that can be trapped as methyl esters or allowed to decarboxylate under mild conditions. This method has been applied to a short synthesis of the pyrrolizidine alkaloid (+/-)-isoretronecanol.
Activation of Fluorescent Protein Chromophores by Encapsulation
作者:Anthony Baldridge、Shampa R. Samanta、Nithyanandhan Jayaraj、V. Ramamurthy、Laren M. Tolbert
DOI:10.1021/ja908870k
日期:2010.2.10
Chromophores related to fluorescent proteins, when sequestered into the "octaacid" capsule, recover their fluorescence, The fluorescence recovery is related to the inhibition of torsional motions within the cavity, implicating the single-bond torsion as an important contributor to internal conversion within this important class of chromophores.