Unusual Stabilization of 1,2‐Diamino Derivatives of Quincorine and Quincoridine by Carbon Dioxide: Persistent Crystalline prim‐Ammonium‐Carbamate Salts and Their Reactivity towards Isatoic Acid Anhydride

Abstract

The reaction of N‐methylisatoic anhydride 1 with a series of quincorine (QCI) and quincoridine (QCD) derivatives furnished the corresponding QCI‐ and QCD‐substituted anthranilic acid amides 4−9. In the synthesis of 4−9, we investigated the influence of the C5 substituent of 2‐aminomethyl derivatives of QCI and QCD on their basicity and polarity and, therefore, on their reactivity towards isatoic acid anhydride. By exposing a number of 2‐aminomethyl derivatives of QCI and QCD to (carbon dioxide from) air, the formation of carbon dioxide adducts 10−15 was observed. In an unusual reaction, we obtained the first set of chiral ammonium carbamates derived from primary amines, which provides a convenient method for purifying and stabilizing aminomethyl derivatives of QCI and QCD. All compounds were fully characterized by spectroscopic methods. In addition, the structure of 11 was proved by X‐ray crystal structure determination. The heterocyclic nitrogen atoms display trigonal‐pyramidal coordination geometries; the amido group is essentially planar. N‐2′ of the ammonium ion is a triple hydrogen bond donor to the carboxylato oxygen atoms of three different carbamate anions. The resulting net effect is a hydrophilic plane parallel to the ab plane. The crystal packing involves six classical hydrogen bonds. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

Recent Advances in the Chemistry of Metal Carbamates

“…Since 2003, many other alkylammonium alkylcarbamates of cyclic amines [ 74 , 75 , 76 , 77 ], substituted amines [ 78 , 79 , 80 , 81 , 82 ] and diamines [ 83 , 84 , 85 ] have been isolated and characterized by IR and NMR spectroscopy, and by X-Ray diffraction in a number of cases. Noteworthy, some of these carbamates were obtained upon air exposure, revealing the capability of the respective amines of trapping CO 2 from the environment [ 74 , 75 , 76 , 81 , 82 , 83 , 84 ].…”

“…The first examples of chiral ammonium carbamates derived from chiral primary amines were described by Neda et al [ 80 ], as obtained by the treatment of amino derivatives of quincorine and quincoridine with carbon dioxide in diethyl ether ( Scheme 3 b). The isolated colorless solids are stable for several days in solution at ambient temperature and thermally stable until 120 °C in a solid state.…”

Recent Advances inCinchonaAlkaloid Chemistry

“…In this simple fashion, even traces of QCI can be removed from 12-NH 2 without recourse to HPLC, distillation or other traditional separation and purification techniques (Scheme 9). [18] Conversely, the chemical fixation of CO 2 by 12-NH 2 can be used for gravimetric analysis. Scheme 9.…”

“…Ammonium carbamate 14; a stable crystalline carbamate salt from 1,2-diamine 12-NH 2 (I. Neda, 2003) Further applications of QCD-and QCI-derived bidentate ligands are beginning to emerge. Although hydrosilylations with QCI-and QCD-derived phosphane ligands afford only low ees (up to 54%), the asymmetric Kumada-Corriu coupling with 2H-QCIphos (12-PPh 2 ) proceeds in up to 85% ee (Scheme 10).…”

Asymmetric calixarene derivatives as potential hosts in chiral recognition processes

“…These acids were now coupled with the C9-amine-quincorine (QCI-C9-NH 2 ) [45], establishing an amide bond. The method of choice was to transform the acids to their corresponding acyl chlorides.…”