Use of the Potassium Ion as a Template for the Selective Derivatization of the Antibiotic X-206

Abstract

The templating effect of potassium ions on the ionophore antibiotic X-206 (1) ensured that most of the hydroxy, hemiacetal, and ether groups were involved in encapsulation of the metal atom, which allowed a selective derivatization at the unbound C(22) position. The mechanism of acylation at C(22) was investigated and the aquired knowledge used to achieve selective reactions on the benzyl ester 8 using a similar metal template protection.

A new method for making acyl fluorides using BrF3

“…Another option used mainly in peptide chemistry, is the reaction of cyanuric fluoride (FCN) 3 on protected amino acids [7]. The most common methods, however, make use of SF 4 or DAST [8] and other reagents based on various forms of HF and other fluorides serving as fluorine source [9]. We present, in this work, yet another way of forming acyl fluorides in very reasonable yields, revolving around reacting carboxylic acids, acyl chlorides or t-Bu esters with BrF 3 .…”

Amino acid fluorides: viable tools for synthesis of peptides, peptidomimetics and enantiopure heterocycles

“…49 The reagent has been used for the conversion of alcohols to uorides, aldehydes and ketones to geminal diuorides. 50 Subsequently DAST (3) 51,52 was employed as an alternative to C 3 F 3 N 3 (Scheme 2). It has several advantages over C 3 F 3 N 3 in terms of absence of a base, simplied work-up and easy elimination of water soluble by-products.…”