Camphor derivatives as chiral auxiliaries in asymmetric synthesis

Synthesis and Reduction of 10-Phthalimidocamphor Oxime

“…16 The following reaction of 2 with potassium phthalimide gave the corresponding 10-phthalimidocamphor (3) in 72% yield. Finally, condensation of 3 with NH 2 OH furnished in 92% yield the expected 10-phthalimidocamphor oxime (4). Next, reduction of the oxime 4 was studied with the aim of preparing mono-protected primary diamine camphor building block 5 (Scheme 1).…”

“…The unique reactivity of camphor enables its derivatization at positions 2, 3, 4, 5, 8-10, as well as selective cleavage of the C1-C2 and C2-C3 bonds ( Figure 1). 1,2 All of the above makes camphor a very desirable starting compound for the preparation of a wide variety of products 3 ranging from natural products 1,2 to chiral auxiliaries, 4,5 ligands in asymmetric synthesis, [6][7][8][9][10] organocatalysts, 11 and NMR shift reagents. 12 Within our continuing study on camphor-based diamines as potential organocatalyst scaffolds, [13][14][15] we recently reported on the synthesis of a novel type of 1,3-diamine-derived bifunctional squaramide orga nocatalysts A prepared from 10-iodocamphor and their application as highly efficient catalysts in Michael additions of 1,3-dicarbonyl nucleophiles to trans-β-nitrostyrenes.…”

“…16 10-Iodocamphor 17 has seen surprisingly limited appli cation as the starting compound, [18][19][20][21][22][23][24] although, it can easily be prepared in sufficient quantities from (1S)-(+)-10-camphorsulfonic acid. 16 Herein we report the results of the synthesis and reduction of 10-phthalimidocamphor oxime (4), which is a potential precursor for the preparation of mono-protected primary diamine camphor building block 5.…”

Behavior of thiosemicarbazones derived from some terpenones under acetylating conditions

“…Bearing in mind the above mentioned influence of camphor versus fenchone topology, 5 we initially attempted the synthesis of the corresponding heterocyclic compounds starting from fenchone thiosemicarbazone 4, and later extended this study to thiosemicarbazones derived from camphor 5 and menthone 6 (see Figure 2). The thiosemicarbazones were synthesized by treatment of the corresponding terpenones with thiosemicarbazide in acid medium, unless otherwise indicated, according to the general procedure previously described.…”

“…Therefore, they are often employed as chiral reagents, intermediates or catalysts in asymmetric synthesis. 5 In order to compare the chirality induction by bicyclic versus monocyclic terpenone structures, the reaction was also studied on menthone, which produces satisfactory diastereoisomeric excesses in other types of reactions. 6 …”