Selective <i>tert</i>-Butyl Ester Deprotection in the Presence of Acid Labile Protecting Groups with Use of ZnBr<sub>2</sub>
作者:Ramesh Kaul、Yann Brouillette、Zohreh Sajjadi、Karl A. Hansford、William D. Lubell
DOI:10.1021/jo0491206
日期:2004.9.1
hydrolysis of tert-butylesters in the presence of other acid-labile groups has been explored by employing α-amino esters and ZnBr2 in DCM. Although N-Boc and N-trityl groups were found to be labile, PhF protected amines were compatible with these Lewis acid deprotection conditions such that a variety of N-(PhF)amino acids were prepared in good yields from their corresponding tert-butylesters.
Rigid Dipeptide Surrogates: Syntheses of Enantiopure Quinolizidinone and Pyrroloazepinone Amino Acids from a Common Diaminodicarboxylate Precursor
作者:Francis Gosselin、William D. Lubell
DOI:10.1021/jo991766o
日期:2000.4.1
phosphonate 12 (PhF = 9-phenylfluoren-9-yl). The practicality of this approach for making azabicyclo[X.Y.0]alkane amino acids was then illustrated by the first synthesis of enantiopure quinolizidin-2-one amino acid 6 in seven steps and 40% overall yield from L-pyroglutamic acid. Hydrogenation of delta-keto alpha,omega-diaminosebacate 18, followed by lactam cyclization and protection, gave quinolizidin-2-one