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Please login to access the full content or check if you have access via16.2.4.2.2 Dibenzo[b,e][1,4]dioxins from the Diels–Alder Reactions of 1,4-Benzodioxin and Benzo[b]furo[3,4-e][1,4]dioxins
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Sakya, S. M.; Yang, J., Science of Synthesis Knowledge Updates, (2012) 1, 232.
The Diels–Alder reaction is a powerful approach to the synthesis of substituted dibenzo[b,e][1,4]dioxins in a single step. For example, the reaction of benzo[b]furo[3,4-e][1,4]dioxins 26 with thiolactone 27 (X = S) in the presence of a catalytic amount of ytterbium(III) trifluoromethanesulfonate gives thiolactone-substituted dibenzo[b,e][1,4]dioxins 28 and 29 in 27–77% yield (Scheme 6).[26] Only ytterbium(III) trifluoromethanesulfonate catalysis gives dehydrated products directly and the major product has been determined to be that with the small (R3) substituent ortho to the carbonyl group (compound 29).[26] The Diels–Alder reaction has also been performed without a catalyst, but this requires acid- or base-catalyzed dehydration of the formed intermediates 30 to give the benzo[b,e][1,4]dioxins 31.[27,28]
Meeeee 8 Meeeeeeee ee Meeeeeeeeee Meeeeee[e,e][8,8]eeeeeee eeee Meeee[e]eeee[8,8-e][8,8]eeeeeee ee Meeee–Meeee Meeeeeee eeee Meeeeeee[88–88]
M8 | M8 | M8 | M | Meeee (%) | Mee | 88 | 88 |
---|---|---|---|---|---|---|
M | Me | Me | M | 88 | – | [88] |
M | Me | Me | M | 88 | 88 | [88] |
M | (MM8)8Me | Me | M | 88 | 88 | [88] |
MMe | (MM8)8Me | Me | M | 88 | 88 | [88] |
M8 | M8 | M8 | M8 | Meeee (%) | Mee | 88 | 88 |
---|---|---|---|---|---|---|
Me | Me | M | MM | 88 | 88 | [88] |
Me | Me | MM8Me | MM8Me | 88 | 88 | [88] |
Me | Me | M | MM | 88 | 88 | [88] |
Mee Meeee–Meeee eeeeeeee eee eeee eeee eeeeeeeeeeee eeeeeee 8,8-eeeeeeeeeee (8) eee 8,8-eeeeeeeeeeeee[e]eeeee (88) ee eeeeeeeee eeeeeee, ee eeee eeeeeeeeeee eeeeeee[e,e][8,8]eeeeee 88 ee eee eeeee eeeeeee (Meeeee 8).[88] Meeee eee eeeeeeee eeeeeeeeee, eee eeeeeee Meeee–Meeee eeeeee 88 ee eeeeeeee eeee ee e eeeee eeeeeee, eee ee eeeee eeeeeeeeeee ee eee eeeeeeeeee eeeeee eee eeeeeeeeeeeee eeee eeeeeee eeee eeeeeeeee (eeeeeeee eee ee eee eeeeeeee ee eee eeee eeeeee), ee eeee eee eeeeee eeeeeee.[88] Meee ee ee eeeeeeee ee eeeeeee eeeeeee ee 8,8-eeeeeeeeeee eeeeeeeeeeeee ee Meeee–Meeee eeeeeeeee eeee eeeeeee eeeeee, eeeee eee eeeee ee ee ee eeeeeeeeee.[88]
Meeeee 8 Meeeeeeee ee e Meeeeeeeeee Meeeeee[e,e][8,8]eeeeee eeee 8,8-Meeeeeeeeee eee 8,8-Meeeeeeeeeeee[e]eeeee ee Meeee–Meeee Meeeeeee[88]
Meeeeeeeeeee Meeeeeeee
Meee- eee Meeeee[8,8-e]eeeeeee[e,e][8,8]eeeeee-8(8M)-eeee 88 (M = M, M) eee 88 (M = M, M); Meeeeee Meeeeeeee:[88]
Meeee-8(8M)-eee (88, M = M; 8.8 eeee) ee eeeeeeee-8(8M)-eee (88, M = M; 8.8 eeee) eee e eeeeeeeee eeeeee ee Me(MMe)8 eeee eeeee ee eee eeeeeeeeeeeee eeeee 88 (8 eeee) eeeeeee eeeeeee ee ee. Mee eeeeeee eee eeeeeee ee e eeeeeeeeeeee eeeeee eeeee ee e eeeeeeeee eeee ee 88–888°M eee 8 e. Meeeeeeeeeee ee eee eeeee eeeeeee ee eeeeee eeeeeeeeeeeeee (eeeeee eee, eeeeee/MeMMe) eeee eee eeeeeee ee eee eeeeeeeeee eeeeeee.
8,88-Meeeeeeeeeeee[e]eeeeeee[e,e][8,8]eeeeee (88):[88]
Me eeee-eeeee eeeee eeeeeeee eeee e eeeeeeee eeeeeee eee eee eeeeeee eeee 8,8-eeeeeeeeeee (8; 888 ee, 8.88 eeee) eee 8,8-eeeeeeeeeeeee[e]eeeee (88; 888 ee, 8.88 eeee) ee eeeee eeeeeee (8 eM). Mee eeeeeee eee eeeeee ee 888°M eee 88 e eeeee eeeee eeee ee eee eeeeee ee ee, eeeeeeee eeee eeeeee eee, eee eeee eeeeeeee ee eeeeee eeeeeeeeeeeeee (eeeeee/MeMMe 8:8) ee eeee eee eeeeeee ee e eeeee eeeee; eeeee: 888 ee (88%); ee 888–888°M; eeeeeeee eeee eeeee eeeeeee ee eee eeeeeeeeeeee 88; eeeee: 8%.
References
[26] | Meeeee, M.; Meeeee, M.; Meeeeeee, M.-M.; Meeeee, M.; Meeeee, M.; Meeeeeee, M.; Meeeee, M.; Meeee, M. M., M. Mee. Meee., (8888) 88, 888. |
[27] | Meee, M.; Meee, M.; Meeee, M. M.; Meeeeeeeee, M.; Meeeeee, M., Meeee. Meeeee., (8888) 88, 8888. |
[28] | Meeeee, M.; Meeeeeee, M.-M.; Meeeee, M.; Meeee, M. M., Meeeeeeeeee, (8888) 88, 88888. |
[29] | Meeee, M.; Meeeee, M.; Meee, M. M., M. Mee. Meee., (8888) 88, 888. |
[30] | Meeee, M.; Mee, M.; Meeeeeee, M.; Meeee, M. M., Mee. M. Mee. Meee., (8888), 8888. |