Diboronic Acid Promoted Entry to N-Protected Serine/Threonine-Derived Weinreb Amides
Direct Synthesis of N-Protected Serine- and Threonine-Derived Weinreb Amides via Diboronic Acid Anhydride-Catalyzed Dehydrative Amidation: Application to the Concise Synthesis of Garner’s Aldehyde: N. Shimada, N. Ohse, N. Takahashi, S. Urata, M. Koshizuka, K. Makino
Synlett 2021, 32, 1024–1028
Weinreb amides are critically important and highly versatile synthetic intermediates in organic chemistry, as they can be efficiently used for the preparation of a wide range of carbonyl compounds. Stereochemically pure functionalized Weinreb amides, such as those derived from serine and threonine, are especially useful, but their synthesis is generally affected by drawbacks such as difficult workup and purification procedures, combined with poor overall atom economy. A novel entry to the title compounds has been recently disclosed by the group of Professors Naoyuki Shimada and Kazuishi Makino from Kitasato University (Tokyo, Japan).
Professor Shimada said: “We have developed an efficient method to synthesize Weinreb amides derived from α-hydroxy-β-amino acids by using unique diboronic acid anhydride (DBAA) catalyst. This protocol can be applied to the concise synthesis of Garner’s aldehyde, which is an important chiral building block.”