Science of Synthesis

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

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.