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Bile Acids as Building Blocks of Supramolecular Hosts

“…We have synthesized 2,2'-bipyridine-4,4'-dicarboxylates ( 29a - d , Figure 18 ) [ 114 ] of four bile acid methyl esters from 2,2'-bipyridine-4,4'-dicarboxylic acid and corresponding bile acid methyl esters by Yamaguchi [ 52 ] reaction. Distinct from our other synthesized bile acid-based dimers [ 84 , 85 , 97 , 98 , 99 ], the most favoured conformation of 29a , obtained from the semi-empirical PM3 calculations, is open (∫-type) structure. Most probably this is caused by the lack of aromatic rings in the heads of the dimer which would stabilize the cleft-type conformation.…”

“…We have synthesized lithocholic acid-based molecular clefts and investigated their conformational preferences and Ag + -cation binding properties both experimentally by NMR measurements and theoretically by MO calculations [ 84 , 85 , 97 , 98 , 99 ]. The structures and yields of these open dimers 22a-i , 23a-c are presented in Figure 12 .…”

“…The cleft-type structure of these compounds was suggested by semi-empirical (PM3 level) calculations [ 85 , 98 , 99 ]. Theoretical calculations and NMR measurements of the synthesized Ag + - complexes of pyridine- n -carboxy ( n = 2-4) derivatives 22d - f and 23a - c of lithocholic acid-based dimers showed that the coordination behaviour of the Ag+-cation is dependent on the isomerism of the pyridine- n -carboxy moiety [ 85 , 98 ].…”

Synthesis and 13C NMR chemical shift assignments of 2,2'-bipyridine-4,4'-dicarboxylates of bile acid methyl esters

“…[1][2][3][4][5][6][7] They also have pharmacological potential to act as carriers of liver-specific drugs, absorption enhancers, and as cholesterol-lowering agents, 8 which have made bile acids extensively studied compounds in chemistry and medicine. We have recently reported synthetic procedures for preparing a lithocholaphane 9 and steroidal molecular clefts containing three arylcarboxy, 10 isomeric pyridine-n-carboxy, 11 and isomeric n-acetoxyphenylcarboxy (acetylsalicylate and its isomers) 12 moieties and their complexation tendencies towards silver(I)-cation. 11 By introducing various heteroatoms, and especially nitrogen containing moieties, into the bile acid derivatives, their coordination spheres for cation binding can be greatly enhanced.…”

“…We have recently reported synthetic procedures for preparing a lithocholaphane 9 and steroidal molecular clefts containing three arylcarboxy, 10 isomeric pyridine-n-carboxy, 11 and isomeric n-acetoxyphenylcarboxy (acetylsalicylate and its isomers) 12 moieties and their complexation tendencies towards silver(I)-cation. 11 By introducing various heteroatoms, and especially nitrogen containing moieties, into the bile acid derivatives, their coordination spheres for cation binding can be greatly enhanced. From this point of view, 2,2'-bipyridine and its derivatives are very tempting structures.…”