Using a threading-followed-by-swelling approach to synthesize [2]rotaxanes.
We have developed a "threading-followed-by-swelling" protocol to synthesize [2]rotaxanes efficiently and atom economically. Our protocol employs cis-1-[(Z)-alk-1'-enyl]-2-vinylcyclopropane units as the termini of the threadlike components; these end groups are converted into more-sizable cycloheptadiene motifs, which function as stopper units, through Cope rearrangements at elevated temperature. We used this approach to synthesize [2]rotaxanes in good yield from [2]pseudorotaxanes featuring either one or two swellable termini to interlock three different types of macrocycle. The chiral centers created by the swelling process were "erased" by hydrogenating the cycloheptadiene termini into the corresponding cycloheptane units, affording achiral molecular [2]rotaxanes as the only final products.
Ko
Jia-Ling
JL
Department of Chemistry, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei, Taiwan, ROC.
Ueng
Shau-Hua
SH
Chiu
Ching-Wei
CW
Lai
Chien-Chen
CC
Liu
Yi-Hung
YH
Peng
Shie-Ming
SM
Chiu
Sheng-Hsien
SH
D006865:Hydrogenation; D046911:Macromolecular Substances / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D015394:Molecular Structure; D043862:Rotaxanes / Q000138:chemical synthesis* / Q000737:chemistry; D012997:Solvents / Q000737:chemistry; D013237:Stereoisomerism
D046911:Macromolecular Substances; D043862:Rotaxanes; D012997:Solvents