An Aldimine Cross‐Coupling for the Diastereoselective Synthesis of Unsymmetrical 1,2‐Diamines

Abstract

No protecting groups are required for the cross‐coupling of N‐monosubstituted α‐aminonitriles with imines. Depending on the workup procedure, highly substituted unsymmetrical 1,2‐diamines or 1,2‐diimines can be prepared in a one‐pot procedure. The diastereoselective reduction of the diimines furnishes either the syn‐ or the anti‐configurated diamines (see scheme).

Microwave‐Assisted Synthesis of Polysubstituted 4‐Quinolones from Deprotonated α‐Aminonitriles

“…[8] The resulting keteneiminate salts can serve as stabilized α-aminocarbanion equivalents in the preparation of pyrrolidines, pyrroles, indoles, diamines, amino alcohols, or imidazoles. [8,9] Their alkylation with α-haloesters yields intermediates that slowly release HCN with formation of enamino esters. [10] In the case of aniline-derived aminonitriles, these compounds are susceptible to the Conrad-Limpach cyclization, which would permit the three-step synthesis of polysubstituted 2-aryl-4-quinolones from an aniline, an aromatic aldehyde, and an α-haloester (Scheme 1).…”

Synthesis of Highly Substituted 2-13C-Imidazolium Salts and Metal NHC ­Complexes for the Investigation of Electronic Unsymmetry by NMR

“…We then turned to the 13 C-labeled imidazolium salts 8, in which the resonances of the carbons C4,5 and the nitrogens N1,3 should be split into doublets. Indeed, the 1 J C,N and 2 J C,C couplings could be easily detected in the 1 H, 15 N HMBC, and 13 C NMR spectra, respectively, and differed in magnitude in agreement with the unsymmetrical substitution. On the other hand, the results obtained with the metal complexes 9a-f were less rewarding.…”

“…the addition of deprotonated α-aminonitriles 4 to aldimines 5 followed by atmospheric oxidation of the resulting enediamines 6, permits facile construction of diimines 7 with four variable substituents. 15 The latter compounds can be cyclized to 1,3,4,5-tetrasubstituted imidazolium chlorides 8 upon reaction with a formaldehyde equivalent such as chloromethyl methyl ether (MOMCl) or paraformaldehyde in the presence of hydrochloric acid (Scheme 1). 16,17 A series of six aminonitriles 3a-f were synthesized by Strecker reaction of the corresponding aldehydes and amines with potassium cyanide in the presence of acetic acid ( Table 1).…”

The reductive decyanation reaction: an overview and recent developments

“…BH 3 ·THF containing NaBH 4 has been used for the reduction of diimines [ 72 – 73 ] and was studied in-depth by Zhang and co-workers in the reductive decyanation reaction. In their work, the cyano group activates the [3 + 2] cycloaddition of azomethine ylides and is then removed to yield 5-unsubstituted pyrrolidines [ 74 ].…”