Direct Electrophilic Diamination of Functionalized Alkenes without the Use of Any Metal Catalysts

Abstract

A new direct electrophilic diamination reaction of alpha,beta-unsaturated ketones and esters has been established without the use of any metal catalysts. Three types of nitriles (CH(3)CN, CH(3)CH(2)CN, and CH(3)CH(2)CH(2)CN) were employed as nucleophilic nitrogen sources. A new mechanism has also been proposed to explain the resulting regio- and stereoselectivity.

Aluminium Powder‐Catalyzed Regio‐ and Stereoselective Aminobromination of α,β‐Unsaturated Carbonyl Compounds and Simple Olefins with the p‐Toluenesulfonamide/ N‐Bromosuccinimide (TsNH2‐NBS) System

“…Al (aluminium, entry 13) is the most active catalyst for the aminobromination of chalcone 1a among the elemental metals powders screened. A loading of 1 mol% aluminium powder was sufficient for a smooth reaction at ambient conditions, affording the desired product in high yield (85%, entry 13) within 8 h. This yield is higher than that of the reaction catalyzed by CuI (68%) and comparable to those catalyzed by MnSO 4 (88%) and V 2 O 5 (87%) reported previously, [6] which were obtained with a catalyst loading of 5 mol%, five times more than in our method.…”

“…To address the contamination of hazard metal residues in the products, the metal-free aminohalogenation has gained greater interest. [6] For example, Wang and co-workers performed aminobromination with the TsNH 2 -NBS system in a ball mill process with up to 75 mol% of the expensive hyperiodine, [7a,b] and used 1.2 equiv. of sulfuric acid to promote the aminochlorination with chloramine-T in water.…”

Methods for direct alkene diamination, new & old

“…151 Furthermore, in the case of the more reactive reagent N,N- dichloro-2-nitrobenzenesulfomamide (NsNCl 2 , 180 ), imidazolination of enones 179 proceeds in the absence of catalyst at room temperature to generate the dichloromethyl adducts (Scheme 41). 152 Interestingly, when conducted in the absence of molecular sieves, addition of 180 proceeds at 50 °C to the corresponding trichloromethyl imidazoline products 181 .…”

Rhodium(II)‐Catalyzed Oxidative Amination

“…The mixture of Rh 2 (O 2 CC 3 F 7 ) 4 and Ph 3 P presumably functions to catalyze aziridinium ion formation, though the mechanistic details of such an event remain unclear. Interestingly, imidazoline synthesis may be promoted with similar efficiency using 20 mol% of a 2:1 Ph 3 P/FeCl 3 complex [110,111]. Although currently confined to a small window of substrates, future investigations of this type of methodology would seem fruitful for discovery.…”