Regioselective Transformations of 2',3'-Seconucleosides into Anhydro Structures and Chiral Crown Ethers

Article abstract of DOI:10.1002/hlca.19920750209

Intramolecular cyclisation of properly protected and activated derivatives of 2',3'-secouridine (= 1-<2-hydroxy-1-<2-hydroxy-1-(hydroxymethyl)ethoxy>-ethyl>uracil; 1) provided access to the 2,2'-, 2,3'-, 2,5'-, 2',5'-, 3',5'-, and 2',3-anhydro-2',3'-secouridines 5, 16, 17, 26, 28 and 31, respectively (Schemes 1-3).Reaction of 2',5'-anhydro-3'-O-(methylsulfonyl)- (25) and 2',3'-anhydro-5'-O-(methylsulfonyl)-2',3'-secouridine (32) with CH2Cl2 in the presence of 1,8-diazabicyclo<5.4.0>undec-7-ene generated the N(3)-methylene-bridged bis-uridine structure 37 and 36, respectively (Scheme 3).Novel chiral 18-crown-6 ethers 40 and 44, containing a hydroxymethyl and a uracil-1-yl or adenin-9-yl as the pendant groups in a 1,3-cis relationship, were synthesized from 5'-O-(triphenylmethyl)-2',3'-secouridine (2) and 5'-O,N⁶-bis(triphenylmethyl)-2',3'-secoadenosine (41) on reaction with 3,6,9-trioxaundecane-1,11-diyl bis(4-toluenesulfonate) and detritylation of the thus obtained (triphenylmethoxy)methyl compound 39 and 43, respectively (Scheme 4).