Determination of the absolute stereochemistry and asymmetric total synthesis of madindolines A and B: a practical improvement to a second-generation approach from the first-generation
In this report, we describe an efficient, highly convergent, stereocontrolled first totalsynthesis and a second-generation synthesis of madindolines A 1 and B 2, potent selective inhibitors of interleukin 6. The key steps include (1) asymmetric oxidative ring-closure reaction of tryptophol 3 to construct a chiral 3a-hydroxyfuroindoline 4 using the modified Sharpless asymmetric epoxidation condition
Diastereoselective Substitution Reactions of Acyclic β-Alkoxy Acetals via Electrostatically Stabilized Oxocarbenium Ion Intermediates
作者:Amanda Ramdular、K. A. Woerpel
DOI:10.1021/acs.orglett.2c01004
日期:2022.5.6
Substitutionreactions of acyclic β-alkoxy acetals proceeded with generally high diastereoselectivities (>90:10) to form the anti product. Mechanistic experiments supplemented with computational studies suggest that, upon activation of the acetal, the resulting oxocarbenium ion is electrostatically stabilized by the β-alkoxy group. This stabilization defines the conformation of the reactive intermediate