Highly Efficient and Practical Pyrrolidine–Camphor‐Derived Organocatalysts for the Direct α‐Amination of Aldehydes

Abstract

A series of pyrrolidine-camphor-derived organocatalysts (1-4) were designed and synthesised. These organocatalysts were used for direct α-amination of aldehydes with dialkyl azodicarboxylates to give the desired α-aminated products in high chemical yields (up to 92 %) and with high to excellent levels of stereoselectivity (up to Ͼ99 % ee). The reactions proceeded rapidly (within 5 min) with low catalyst loading (5 mol-%) at ambient temperature. Enantioselective aminations of asymmetric α,α-disubstituted aldehydes in the cata-

Synthesis and structural elucidation of novel camphor‐derived thioureas

“…Those are mainly five‐ and six‐membered cyclic sulfonyl hydrazine derivatives prepared from camphor sulfonic acid 11–14. However, there are also more noncovalent camphor‐derived organocatalysts, the bulk of them comprised of pyrrolidinyl–camphor–derived bifunctional organocatalysts, where both camphor and pyrrolidine chiral frameworks, connected with an appropriate linker, act in synergy 15–24. All the above mentioned camphor‐derived organocatalysts have been prepared via derivatization of camphor i.e., camphorsulfonic acid at positions 2 and/or 10 (Fig.…”

Synthesis of 2‐(3‐(3,5‐bis(trifluoromethyl)phenyl)thioureido)‐3‐((dimethylamino)methyl)camphor organocatalysts

“…1). [27][28][29][30][31][32][33][34][35][36] To the best of our knowledge, we could not find any 3,5bis(trifluoromethyl)phenyl thiourea-derived bifunctional organocatalysts with camphor as the exclusive chiral framework. Considering camphor's vast potential for chemical manipulation and our previous experiences with monofunctional camphor-derived thioureas prompted us to investigate the possibility to prepare novel bifunctional thiourea camphor derivatives, preferably in a stereo-divergent synthesis.…”

“…Concerning the camphor‐derived noncovalent organocatalysts, the vast majority represent the pyrrolidinyl–camphor‐derived bifunctional organocatalysts, where both camphor and pyrrolidine chiral frameworks, connected with an appropriate linker, act in synergy (Fig. ) …”

Synthesis and Structural Characterization of Novel Camphor‐derived Amines

“…It undergoes a wide variety of chemical transformations that, at first glance, functionalize inactivated positions. 1,2 All of the above makes camphor a very desirable starting material for the preparation of a wide variety of products ranging from natural products 1,2 to chiral auxiliaries, 3,4 ligands in asymmetric synthesis, [5][6][7][8][9][10] organocatalysts, [11][12][13][14][15][16][17][18][19][20][21] NMR shift reagents, 22 and others.…”