Efficient synthesis of 8-oxa-bicyclo[3.2.1]octane derivatives from d-arabinose

Our studies of the TIBAL-promoted Claisen rearrangement reaction and ring-closing metathesis (RCM) resulted in the development of an efficient synthetic route to polyfunctional seven-membered carbasugar synthons from d-arabinose. Moreover, the construction of 8-oxa-bicyclo[3.2.1]octane derivatives 10 and 13 was achieved by BCl3 or iodide-promoted intramolecular electrophilic addition reactions, which were regio- and stereoselective.

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2,5-Anhydro-3,4,6-tri-O-benzyl-1-iodo-5-vinyl-l-manno-hexitolC29H31IO4[α]D20=+18.1 (c 0.09, CH2Cl2)

(1R,2R,3R)-4-Benzyloxymethyl-2,3-dibenzyloxycyclohepta-4-ene-1-olC29H32O4[α]D20=-63.1 (c 0.08, MeOH)Absolute configuration: (1R,2R,3R)

(1S,2R,3R)-4-Benzyloxymethyl-2,3-dibenzyloxycyclohepta-4-ene-1-olC29H32O4[α]D20=-28.4 (c 0.12, MeOH)Absolute configuration: (1S,2R,3R)

(1S,2S,3R,5R)-4-Methylene-8-oxa-bicyclo[3.2.1]octane-2,3-diolC8H12O3[α]D20=-16.7 (c 0.10, MeOH)Absolute configuration: (1S,2S,3R,5R)

(1S,2S,3S,4R,5S)-2,3-Dibenzyloxy-1-benzyloxymethyl-4-iodo-8-oxa-bicyclo[3.2.1]octaneC29H31IO4[α]D20=-38.8 (c 0.37, CH2Cl2)Absolute configuration: (1S,2S,3S,4R,5S)