A convergent strategy for the synthesis of beta-cyclodextrin analogues is reported, utilizing preferential cyclodimerization of an azido-alkyne trisaccharide via Cu(I)-catalyzed [3 + 2] dipolar cycloaddition of the alkyne and azide functional groups. The resultant oligosaccharide macrocycle retains the binding propensity of cyclodextrins, as demonstrated by the similar ANS association constants measured for macrocycle 1 and beta-cyclodextrin. This new synthetic strategy opens up new avenues for modular preparation of functionally diverse cyclodextrin analogues that are otherwise inaccessible.

[structure: see text] A highly convergent strategy for the synthesis of C3- or C2-symmetric oligosaccharide macrocycles is reported. Molecular modeling indicates these macrocycles possess sterically congested cavities. Weak host-guest interactions are observed that should be beneficial for applications such as functionalized molecular pores.

General Information S1 Experimental Procedures S3Modeling Images S19 1 H and 13 C NMR Plots S22 General Procedures. All reactions were performed in flame-dried modified Schlenk (Kjeldahl shape) flasks fitted with a stopper or sealed tubes under a positive pressure of argon, unless otherwise noted. Air-and moisture-sensitive liquids and solutions were transferred via syringe or stainless steel cannula. Organic solutions were concentrated by rotary evaporation below 35 °C at ca. 25 Torr or by evaporation via a stream of dry nitrogen gas. Flash column chromatography was performed employing 230-400 mesh silica gel. Thin-layer chromatography was performed using glass plates pre-coated to a depth of 0.25 mm with 230-400 mesh silica gel impregnated with a fluorescent indicator (254 nm). TLC plates were visualized with UV light and/or ceric ammonium molybdate (CAM). All saccharide intermediates and diphenylsulfoxide were dried by removal of water as an azeotrope with toluene. Materials. Dichloromethane (CH 2 Cl 2 ), triethylamine (Et 3 N), trimethylsilylazide (Me 3 SiN 3 ), and 1,8-diaza[5.4.0]bicycloundec-7-ene (DBU) were distilled from CaH 2 and

The common and biogenetically important sesquiterpene guaiol yields a deep purple color when treated with electrophilic bromine reagents. This interesting color reaction was observed over fifty years ago, but the chemistry of this process has not been investigated. Herein, we present the chemistry of the guaiol color reaction.