Neuere Methoden der präparativen organischen Chemie IV Synthesen mit heterocyclischen Amiden (Azoliden)

Cyclic polymers: Synthetic strategies and physical properties

“…An initiation and ring-opening polymerization process analogous to that for primary amines yields peptide chains with two reactive endgroups (Scheme 28). It is known for many decades 109 that imidazolides of carboxylic acids are several orders of magnitude more electrophilic than normal amide groups and react easily with amines at [20][21][22] C, and with alcohol or water at higher temperatures. Therefore, the imidazole-initiated peptide chains can react with each other producing chain extension by condensation steps or they can cyclize (Scheme 28).…”

The Preparation of 1,1′-Carbonyl- and 1,1′-Sulfinyl-dipyrazoles and their Reactions with Carbonyl Compounds

“…A mixture of 1 (0.90 mmol), dry acetone (-5 ml), and cobalt(l1) chloride (-4 nlg) was heated in a sealed tube at 90-95' for 16 h to liberate C 0 , quantitatively (only traces of CO, were detected at 25"). The solid product was purified by zone fractionation under vacuum to yield 2,2-bis(3-methylpyrazol-1-yl)-propane (4) ' co' the appropriate sodium pyrazolide salt with either phosgene or thionyl chloride, in a manner analogous to the procedures reported in the literature for the synthesis of l,lf-sulfinyldiimidazole (5) and various derivatives of 1,l'-carbonyldipyrazole (I, 3, 6-8) and I, 1 '-carbonyldiimidazole (9). Co~npound 1 is obtained as a single substance, there being no evidence for the formation of the isomeric 1,l '-carbonylbis-(5-methylpyrazole) or the mixed isomer 14 (es.…”

2-(Isopropylideneaminooxy)propion-p-bromoanilide

“…As no attack at the asymm~.tric centre is involved in this correlation, the S configuration is unambiguously established for (+)-TAPA. In order to confirm this finding, an X-ray analysis was carried out on (-)-(4), which is readily accessible from (-)-(2) by aminolysis of the corresponding carboximidazolide (Staab, 1962) with p-bromoani!ine.…”