Synthesis and Structural Characterization of Novel Camphor‐derived Amines

Abstract

Two novel 4-substituted camphidine derivatives 10a,b have been prepared from (+)-camphor (1) in five steps, the Beckmann rearrangement being the bottleneck of the synthesis. Isoborneol derivative 5b, formed as a side product during the hydrogenation of arylidene ketone 3b, under Beckmann rearrangement conditions yielded interesting novel rearrangement products 11 and 12. (1S)-(+)-Camphorquinone (13) was transformed into diamines 15 and 16 in two steps, the former being cyclized into an imidazoline salt 17, an N-heterocyclic carbene precursor. The structures of all novel compounds have been meticulously characterized using NMR techniques and/or single crystal X-ray analysis.

Toward a Chemical Constructor: A Lego-Like Approach for Formal α-Alkylation of Cyclic Ketones

“…Yellowish oil, yield 95% (26.2 g). 1 H NMR (500 MHz, chloroform-d) δ 6.70 (d, J = 9.9 Hz, 1H), 4.13 (s, 2H), 3.85 (12); 67 (35); 68 (10); 77 (28); 79 (54); 80 (12); 81 (36); 82 (16); 83 (76); 91 (27); 93 (23); 94 (14); 95 (20); 99 (16); 105 (10); 107 (24); 111 (50); 112 (11); 113 (22); 121 (26); 122 (12); 123 (12); 135 (24); 149 (14); 151 (36); 164 (23) 34.…”

“…int. ): 39 (31); 41 (40); 43 (16); 53 (25); 54 (16); 55 (42); 65 (15); 66 (13); 67 (47); 68 (12); 69 (10); 77 (25); 79 (39); 80 (10); 81 (46); 82 (12); 83 (38); 84 (23); 91 (20); 93 (12); 94 (14); 95 (16); 96 (13); 99 (100); 107 (14); 109 (11); 111 (22); 112 (51); 113 (22); 121 (13); 125 (14); 137 (15); 177 (16); 193 (10) [M − H] + ; 194 (15) [M] + .…”

“…20 The reaction of intermediate enaminones with Li/Mg C-nucleophiles could be used as an alternative to crotonic condensation (Figure 1, step B). Earlier, this transformation was applied in special cases like steroids, 21 opioids, 22 and ligands, 23 but now it is "neglected" and its scope and scalability are still unclear. 24 Here, we expand the scope of formal α-alkylation of ketones from simple methylation to diverse 1°and 2°alkyl substituent installations.…”

Stereodivergent Synthesis of Camphor-Derived Diamines and Their Application as Thiourea Organocatalysts

“…Within our continuing study on camphor-based diamines as potential organocatalyst scaffolds with camphor as the exclusive chiral framework, we previously reported on camphor C2-, C3-, and C8-derived 1,2-, 1,3-, and 1,4-diamines [ 40 , 41 , 42 ]. The corresponding noncovalent thiourea organocatalysts have been evaluated for the 1,4-addition of dimethyl malonate to trans -β-nitrostyrene.…”

Strecker degradation of amino acids promoted by a camphor-derived sulfonamide

“…1 ) is known to react with amines through the C=O group (position 3, Fig. 1 ) forming imine camphor compounds [ 2 , 15 – 17 ], one could expect that an amine condensation with the C=O double bond of oxoimine 1 would also lead to imine or aminal (carbinolamine)-type compounds. Thus, we set out to investigate the reaction of 1 with amino acids.…”