Hydroamination of isocyanates and isothiocyanates by alkaline earth metal initiators supported by a bulky iminopyrrolyl ligand

Abstract

Synthesis of heteroleptic and homoleptic alkaline earth metal complexes supported by bulky bis-iminopyrrolyl ligands are reported. The catalytic hydroamination of isocyanates and isothiocyanates with aryl amines using calcium complex is presented.

A binuclear aluminium complex as a single competent catalyst for efficient synthesis of urea, biuret, isourea, isothiourea, phosphorylguanidine, and quinazolinones

“…A most plausible mechanism of biurets formation from the secondary amines and isocyanates using Al catalyst 3a is proposed based on previous studies. 16,59 It was proposed that in the initial step, more nucleophilic secondary amine reacts on both the Al-centers of electrophilic pre-catalyst to form active catalytic species aluminum amine which further participates in several catalytic steps to give the desired product. The detailed mechanism and scheme are provided in the ESI (Scheme S1 †).…”

“…[5][6][7][8][9][10][11][12] In contrast to the signicantly developed catalytic hydroamination of alkynes, alkenes, and carbodiimides to form C-N bonds, [13][14][15] catalytic hydroamination of isocyanates, leading to urea derivatives, have been explored only by some group 2, titanium, zinc, actinide complexes, etc. [16][17][18][19][20][21][22] The urea derivatives are useful across a range of biological systems, pharmaceuticals, agrochemicals, synthetic chemistry, supramolecular chemistry, and materials chemistry. [23][24][25][26][27][28][29][30][31] Moreover, the synthesis of derivatives containing multiple urea moieties within one molecule, such as biuret and triuret derivatives from monourea, is quite challenging since the nucleophilic nature of urea compared to secondary amines is considerably less.…”

Efficient Hydroboration of Esters and Nitriles Using a Quinazolinone‐Supported Titanium(IV) Multitasking Catalyst

“…Our research group has been actively involved in developing a number of efficient catalytic systems using metals such as alkali, alkaline earth metals, and titanium that are readily available, low‐cost, relatively low‐toxic, and more sustainable, for various organic transformations [44–50] . We have recently developed efficient protocols for the chemoselective hydroboration of esters and nitriles using a readily available neosilyllithium [51] (LiCH 2 SiMe 3 ) complex and an aluminum alkyl complex [ κ 2 ‐{2‐F−C 6 H 4 NP(Se)Ph 2 } 2 Al(Me)] as pre‐catalysts to furnish the corresponding boron compounds under mild conditions in high yield.…”

“…[3,[41][42][43] Our research group has been actively involved in developing a number of efficient catalytic systems using metals such as alkali, alkaline earth metals, and titanium that are readily available, low-cost, relatively low-toxic, and more sustainable, for various organic transformations. [44][45][46][47][48][49][50] We have recently developed efficient protocols for the chemoselective hydroboration of esters and nitriles using a readily available neosilyllithium [51] (LiCH 2 SiMe 3 ) complex and an aluminum alkyl complex [k 2 -{2-FÀ C 6 H 4 NP(Se)Ph 2 } 2 Al(Me)] as pre-catalysts to furnish the corresponding boron compounds under mild conditions in high yield. The Ti IV complex supported by dianionic amidophosphine-borane ligand, [{Ph 2 P(BH 3 )N} 2 C 6 H 4 Ti-(NMe 2 ) 2 ] has also been synthesized and employed by our group as an effective catalyst for the highly chemoselective hydroboration of terminal alkynes and nitriles.…”

Facile Synthesis of Benzimidazole and Benzothiazole Compounds Mediated by a Zinc Precatalyst Supported by an Iminopyrrole‐Morpholine Ligand

“…Zinc precursors are inexpensive, environmentally benign, bench stable, and safe for large-scale application. In the course of our research, we have utilized several earth-abundant metal catalysts in the hydroboration, [46][47][48][49][50][51][52][53][54][55][56][57][58] hydroamination, [59][60][61][62][63][64][65][66][67][68][69][70] and hydrosilylation [71][72][73][74][75][76][77][78][79][80][81][82][83] of various functional groups. We have also used metal catalysts in the synthesis of α-aminonitriles.…”