Synthesis of optically active seven-membered 1,5-anhydrocarbasugars and 1,4,5-tribenzoyloxy-2-ethoxy cycloheptanes via [5+2] cycloaddition |
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Authors: | Arun A YadavPrajakta S Sarang Manishankar SauSrinath Thirumalairajan Girish K Trivedi Manikrao M Salunkhe |
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Institution: | a Department of Chemistry, The Institute of Science, 15, Madam Cama Road, Mumbai 400 032, India b Department of Chemistry, Indian Institute of Technology Bombay, Mumbai 400 076, India c Toronto Research Chemicals Inc., 2, Brisbane Road, North York, ON M3J 2J8, Canada d Department of Chemistry, Shivaji University, Kolhapur 416 004, India |
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Abstract: | 5+2] Cycloaddition followed by asymmetric dihydroxylation procedure have been utilized to prepare novel cyclitols. Accordingly, rac-2α-hydroxy-6α-ethoxy-1,5-anhydro cyclohept-3-ene, 10 derived from 5+2] cycloaddition of 3-oxidopyrylium ylide and vinyl ether has been recognized as a seven-membered carbasugar equivalent and elaborated to 1,4,5-tribenzoyloxy-2-ethoxy cycloheptanes through a flexible, regio- and stereoselective strategy involving Sharpless asymmetric dihydroxylation conditions to resolve the compounds obtained. The structures and relative configurations of newly synthesized (+)-2α-acetoxy-6α-ethoxy-3β,4β-dihydroxy-1,5-anhydro cycloheptane ((+)-12)); (−)-1β,4β,5β-tribenzoyloxy-6α-ethoxy cycloheptane ((−)-17) and (+)-1α,4α,5α-tribenzoyloxy-6β-ethoxy cycloheptane ((+)-17) are unambiguously established by single crystal X-ray analysis and duly supported by 1H and 13C NMR spectroscopy data. |
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Keywords: | Carbasugar Cyclitol 3-Oxidopyrylium ylide Cycloaddition Stereocontrol |
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