You are using Science Of Synthesis as a Guest.
Please login to access the full content or check if you have access via18.2.4.1.12.1 Variation 1: Addition of Isocyanic Acid
Please login to access the full content or check if you have access via
Braverman, S.; Cherkinsky, M.; Birsa, M. L., Science of Synthesis, (2005) 18, 122.
In general, alkenes react with isocyanic acid with difficulty; however, introduction of electron-donating substituents increases the reactivity toward isocyanic acid significantly. For example, α,β-unsaturated ethers, such as butyl and ethyl vinyl ethers, vinyloxyethyl methacrylate, and butyl isopropenyl ether, produce α-alkoxy isocyanates, e.g. 147, in good yields (Scheme 83).[405–407] An excess of isocyanic acid is required in order to avoid the side reaction of polymerization of the unsaturated ethers. Under heating and in the presence of a catalyst (4-toluenesulfonic acid, boron trifluoride–diethyl ether complex, iodine) some other substrates, including isobutene, isoprene, styrene, and α-methylstyrene, can add isocyanic acid, generated in situ from cyanuric acid.[408] Bicyclic alkenes, including norbornene, 2-ethylidenenorbornane, norbornadiene, and dicyclopentadiene, react with isocyanic acid at 120°C in the presence of 4-toluenesulfonic acid to give the corresponding isocyanates.[409]
Meeeee 88 Meeeeeee ee Meeeeeeee Meee ee Meeeeee[888–888]
Meeeeeee ee eeeeeee eeee eeeeeeeee eeee ee eee eeeeeeee ee eeee-eeeee eeeeeeeeeeee eeeeeee ee eee eeeeeeeee ee β-eeeeeeeeeee eeeeeeeeeee 888 (Meeeee 88).[888]
Meeeee 88 Meeeeeeee ee β-Meeeeeeeeee Meeeeeeeeee[888]
Meeeeeeeeeee Meeeeeeee
8,8-Mee(8-eeeeeeeeeeeeeeeeee)eeeeee (888); Meeeeee Meeeeeeee:[888]
Me e eeee ee MMMM (88 e, 8.88 eee) eee eeeee MeMM (8.8 e) ee eeeeeee (888 eM) (MMMMMMM: eeeeeeeeee), eeeeeeee eeeeee eeeeeee eeeee (88.8 e, 8.8 eee) eee eeeee eeee e eeeeee ee 88 eee. Mee eeeeeee eee eeeeee ee 88°M eeee eeeeeeee eee e eeeeeee 88 eee, eee eeee eeeeeee eee eee eeeeee MMMM eeee eeeeeeeee eee eeeee eeeeeee eeeeeeee. Mee eeeeeee eee eeeee eeeeeeeee eeeee eeeeeee eeeeeeee ee eeee eee eeeeeee; eeeee: 88.8 e (88%); ee 88°M/8.8 Meee.
References
[405] | Meeeee, M. M.; Meeeeeee, M. M., M. Mee. Meee., (8888) 88, 8888. |
[406] | Meeeee, M.; Meeee, M., M. Meeee. Meee., (8888) 888, 888. |
[407] | Meeeee, M.; Meeeeeeeeee, M., M. Meeee. Meee., (8888) 888, 888. |
[408] | Meeeee, M. M.; Meeeeeee, M. M., M. Mee. Meee., (8888) 88, 888. |
[409] | Meeee, M., Mee. Meee. Meeeeeeee, (8888) 8, 8. |
[410] | Meeeee, M. M.; Meeeee, M. M., MM 8 888 888, (8888); Meee. Meeee., (8888) 88, 88888. |
Meeeeee Meeeeeeeeee
- 8.Meeeee-Meee, (8888) M 8, 888.
- 8.Meeeee-Meee, (8888) M 8, 888.
- 8.Meeeee-Meee, (8888) M 88e8, 888.
- 8.Meeeee-Meee, (8888) M 88e8, 888.