Acylation and Alkoxycarbony-lation of Benzoxazoline-2-thione and Benzothiazoline-2-thione
摘要:
Acylation of benzoxazoline-2-thione (1) and benzothiazoline-2-thione (2) with acetic anhydride (3) and acyl chlorides (4) gave N-acyl (5, 6) and/or S-acyl (7, 8) derivatives depending on the nature of acylating agents and bases used. Alkoxycarbonylation of 1 with aralkyl chlorocarbonates (9) gave N-alkoxycarbonyl derivatives (10) mainly, while that of 2 with aralkyl chloroccarbonates (9) gave S-alkoxycarbonyl derivatives (12) exclusively. Photolysis of N-acyl derivatives (5 or 6) in the presence of alcohols afforded 1 or 2, respectively, together with esters (16).
Abstract A synthesis of a series of N‐alkoxycarbonyl mercaptobenzothiazoles (MBTs) and their application as reagents for chemoselective protection of amino group are presented herein. It was shown that all newreagents, Z‐MBT, Fmoc‐MBT, Phoc‐MBT, and Tec‐MBT, are highly effective in the selective N‐alkoxycarbonylation of (S)‐isoserine. The transformation is a simple, fast, and low‐cost protocol, which
摘要 本文介绍了一系列 N-烷氧基羰基巯基苯并噻唑 (MBT) 的合成及其作为化学选择性保护氨基试剂的应用。结果表明,所有新试剂 Z-MBT、Fmoc-MBT、Phoc-MBT 和 Tec-MBT 在 (S)-异丝氨酸的选择性 N-烷氧基羰基化中都非常有效。该转换是一种简单、快速且低成本的协议,适用于放大实验。起始 MBT 在过程结束时完全回收,这是该方法的另一个优点。在氨基糖苷类抗生素异帕米星的合成中,庆大霉素 B 和 (S)-异丝氨酸在肽型偶联之前的选择性保护也证明了 Z 试剂的效率。
Fluorinated Copolypeptide‐Stabilized Microbubbles with Maleimide‐Decorated Surfaces as Long‐Term Ultrasound Contrast Agents
Amphiphilic fluorinated copolypeptides are used to stabilize perfluorocarbon-filled microbubbles (MBs) with the formation of highly stable ultrasound (US) contrast agents. Moreover, the US signals can be remarkably enhanced by the in situ reaction of peripheral maleimide moieties with plasma proteins without compromising the stability of MBs, outperforming commercially available SonoVueTM MBs in in