Facile Synthesis of Furan-3,4-diacetates

✍ Scribed by Ernest Wenkert; Haripada Khatuya

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: German
• Weight: 80 KB
• Volume: 81
• Category: Article
• ISSN: 0018-019X
• DOI: 10.1002/(sici)1522-2675(19981216)81:12<2370::aid-hlca2370>3.0.co;2-u

✦ Synopsis

A procedure for bis-cyclopropanation of furans with ethyl diazoacetate or methyl a-diazopropionate under dirhodium-tetraacetate catalysis is presented. Treatment of the products with ethanolic HCl furnished furan-3,4diacetates.

Helvetica Chimica Acta ± Vol. 81 (1998)

2 ) The monocyclopropanated compound 2b could be obtained (51%) from the non-polar portion of the products of a Rh-catalyzed decomposition of methyl a-diazopropionate in furan. Colorless, sweet-smelling oil. 1 H-NMR: 0.93 (s, Me); 2.84 (dd, J 3, 6, HÀC(4a)); 3.68 (s, MeO ); 4.74 (d, J 6, HÀC(1a)); 5.26 (t, J 2.6, HÀC(4)); 6.45 (d, J 2.4, HÀC(3)). 13 C-NMR: 5.0 ( Me); 18.5 (C(6)); 36.9 (C(5)); 51.7 ( MeO ); 70.4 (C(1)); 102.1 (C(4)); 148.4 (C(3)); 174.8 (CO ). 3 ) Bis-cyclopropanations could be executed also on furans with side chains containing functional groups (e.g., furan-2-acetate 1d [6]): 1d 3 5d (59%). Colorless oil. 1 H-NMR: 1.2 ± 1.3 (m, 3 Me); 1.96 (d, J 4, CHCOOEt); 2.29 (d, J 3, CHOOEt); 2.46 (dd, J 3, 4, HÀC(5), HÀC(6)); 2.80 (d, J 17, 1 H, CH 2 OOEt); 2.92 (d, J 17, 1 H, CH 2 OOEt); 3.84 (d, J 6, HÀC(1)); 4.0 ± 4.2 (m, 3 CH 3 CH 2 ). 13 C-NMR: 13.8 ( Me); 13.9 (2 Me); 26.4 (CH 2 COOEt); 31.4 (CHCOOEt); 31.6 (CHCOOEt); 32.4 (C(5) or C(6)); 32.6 (C(5) or C(6)); 60.3 ( MeCH 2 ); 60.5 ( MeCH 2 ); 60.6 ( MeCH 2 ); 62.8 (C(1)); 70.2 (C(3)); 169.7 (CH 2 COOEt); 170.0 (CO ); 170.1 (CO ). Similarly, 1e 3 7b. Colorless oil. 1 H-NMR: 1.41 (s, Me); 1.54 (s, Me); 2.04 (s, MeCO ); 2.28 (d, J 6, HÀC(5)); 2.54 (s, HÀC(5) or HÀC(6)); 3.66 (s, MeO ); 3.69 (s, MeO ); 3.84 (d, J 6, HÀC(1)); 4.45 (s, CH 2 ). 13 C-NMR: 7.7 ( Me); 8.9 ( Me); 20.3 ( MeCO ); 27.2 (C(4) or C(7)); 30.6 (C(4) or C(7)); 31.2 (C(5) or C(6)); 32.6 (C(5) or C(6)); 52.0 ( MeO ); 52.2 ( MeO ); 62.9 (CH 2 ); 68.2 (C(1)); 74.7 (C(3)); 170.1 (CO ); 171.6 (CO ); 172.3 (CO ). 4 ) Ring opening of 5d (CF 3 CO 2 H/1208/2 h) afforded triester 9d (57%). Colorless liquid. 1 H-NMR: 1.2 ± 1.3 (m, 3 Me); 3.42 (s, CH 2 ÀC(3) or CH 2 ÀC(4)); 3.45 (s, CH 2 ÀC(4) or CH 2 ÀC(3)); 3.66 (s, CH 2 ÀC(2)); 4.1 ± 4.3 (m, 3 CH 2 O); 7.34 (br. s, HÀC(5)).