A Synthetic Approach to Diverse 3-Acyltetramic Acids via <i>O</i>- to <i>C</i>-Acyl Rearrangement and Application to the Total Synthesis of Penicillenol Series
efficient approach to medicinally important α-branched 3-acyltetramicacids, the key reaction of O- to C- acyl rearrangement using α-amino-acid-derived 4-O-acyltetramic acids was extensively examined in the presence of various metal salts. Use of CaCl2 or NaI dramatically changed the results in the reaction efficiency and rapidly brought about the desired α-branched 3-acyltetramicacids in markedly