De-Qi Yuan

Guest-induced conformational change in a flexible host: mono-altro-β-cyclodextrin †

Mono-altro--cyclodextrin 1 ,a -cyclodextrin with one of the seven glucose units being configurationally changed to an altrose, is shown to be a flexible host undergoing a distinct conformational change within its altropyranose geometry upon intracavity inclusion of adamantanecarboxylate, thus representing an induced-fit model of binding rather than one following the rigid lock-and-key type pattern.

Selective synthesis and structure determination of 6A,6C,6E-tri(O-sulfonyl)-β-cyclodextrins

Abstract By reacting with a rigid disulfonyl chloride, β-cyclodextrin 6-tosylate is readily disulfonylated for the first time to give 6 A ,6 C ,6 E -trisulfonylated β-cyclodextrins in good yields, which represents an efficient novel method for the regio-selective preparation of 6 A ,6 C ,6 E -trifunctionalized β-cyclodextrins.

Selective Mono- and Bis-Oxidation of 2,6-bis(Hydroxy-methyl) phenols with Active Manganese Dioxide

Abstract Selective mono- and bis-oxidations of 2,6-bis(hydroxy-methyl) phenols with active Mn 2 were realized, giving 2-hydroxy-3-hydroxymethyl benzaldehydes and 2-hydroxyisophthalaldehydes in good yields. The influence of oxidant activity, reaction solvent and temperature on the selectivity were investigated, and favorable conditions developed.

Molecular sugar bowl: γ-cyclodextrin with a disaccharide floor

Abstract A series of molecular sugar bowls composed of a γ-cyclodextrin wall and a trehalose floor have been synthesized by reacting 6A,6X-deoxy-6A,6X-dimercapto-γ-cyclodextrin and 6,6′-deoxy-6,6′-diiodotrehalose.

Direct Imidazolylmethylation of Phenols

Abstract Direct imidazolylmethylation of phenols was realized by Mannich reaction of phenols with paraformaldehyde and imidazole.

DOES THE ABNORMAL RING OPENING OF CYCLODEXTRIN-2,3-EPOXIDE HAVE GENERALITY?

Abstract Na2S has been found to attack the C2 of β-cyclodextrin mannoepoxide 1 more easily than various other nucleophiles, and with the subsequent CD-2-S− only the abnormal ring opening of 1 has been observed.

β-Cyclodextrin-TEBA: A New Catalyst System For Selective Synthesis of α-Hydroxyacids

Abstract The presence of β-cyclodextrin (β-CD) and triethylbenzyl ammonium chloride (TEBA) favors the one-pot reaction of aromatic aldehydes, chloroform and sodium hydroxide to give α-hydroxyarylacetic acids in 81% ∼ 89% yields.

SYNTHESIS OF NOVEL CYCLODEXTRIN TRIMERS

Abstract CD trimers (3 and 6) and CD dimers (4 and 7) have been synthesized by reaction of 6-deoxy-6-hydroxyethylamino-β-CD (1) with corresponding 1,3,5-tri(bromomethyl) benzene (2) or 1,3,5-tri (bromomethyl)-2,4,6-trimethylbenzene (5) in the presence of base.

Synthesis of Novel Squarylium Cyclophanes

Abstract A series of novel squarylium cyclophanes containing one or two diaminosquaraine units have been synthesized by direct condensation of squaric acid and corresponding diamines in highly diluted n-butanol-toluene solutions. †Present address: Department of Chemistry, Columbia University, New York, NY 10027.