Science of Synthesis

Braverman, S.; Cherkinsky, M.; Birsa, M. L., Science of Synthesis, (2005) 18, 156.

Isocyanates in which the NCO group is conjugated with another multiple bond (e.g., C=C, C=O, C=N, C=S) may react in cycloaddition reactions with varying periselectivity: they can act either as a 2π-electron component and afford different [2+2] adducts or as a 4π-electron component and give [4+2] cycloadducts. Thus, trichloroacetyl isocyanate reacts with various vinyl ethers and sugar vinyl ethers to give a mixture of both products (‌Scheme 144‌).[‌565‌,‌571‌] Unlike acyl isocyanates, thioacyl isocyanates react with dienophiles exclusively in [4+2] fashion. For example, ethoxy(thiocarbonyl) isocyanate with some ketones and aldehydes, including α,β-unsaturated aldehydes, affords 6H-1,3,5-oxathiazin-6-ones ‌278‌ (‌Scheme 147‌).[‌572‌]

‌Meeeee 888‌ [8+8]-Meeeeeeeeeeee Meeeeeeee ee Meeeeeee Meeeeeeeeee[‌888‌]

Meeee eeeeeeeeeee eeee eeee eeeee ee eeeee ee eeeeeeeee eeeeeeee 8-eeeeeeee eeeeeeeeeee. Meeeeeeee ee eeeee eeeeeeeeeee eeee eeeeeeeeeee eeeeeeee-eeee 8,8-eeeeeee eeeeeeee, eeeeeeeee eeeeeeee,[‌888‌,‌888‌] eeeee eeeeeeee,[‌888‌] eee eeeeeee,[‌888‌] eee eeeeee e eeeee eeeeee ee 8-eeeeeeee eeeeeee (‌Meeeee 888‌). Mee eeeeeee, eeeeeee ee ee eeeee eeeee eeeeeee ee eeeeeeee-8-eeee eeeeeeeeee eee 8-eeeeeeeeeeeeeeeeeee-8-eee (‌888‌) ee eeeeeeeee eeeeeee eeeeeeee eee eeeeeeeeeeeeeeeeeeeeeeeee ‌888‌ ee e eeeeeeeee eeeeeeee eeeeeee ee 88% eeeee.[‌888‌] M eeeeeee ee eeeee eeeeeeeeee eee eeeeeee eeeeeeee eeee eeeee eeeeeeee eeeeeeee ee eeeeeee eeeeeee. Me e eeeeeee eeeeeeeeeee, eee eeeeee eeeeeee ee eeeee eeeeeeeeeeee eeeeee eeee eeeeeeeeee ‌888‌ ee eeeeeee ee eeeeeeee eeeee eee eeeeeee 8-eeee-8-eeeeeee-8-eeeeeeee ‌888‌ ee eeee eeeee.[‌888‌] M eeeeeee ee eeeee eeeeeeeeeee eeeeeeeeeee ee e eeeeee [8+8] eeeeeeeeeeeee eeee eeeeeee, eeeeeeeee ee eeee(MM) eeeeeee eeeeeeeee eeeeeeeeeeeee ee 8-eeeeeeeeeeeeeeeeee (‌888‌), ee eeeeeee eeeeeeeeeeeeeeee eee eeeeeeeeeeeeeeeeeeeee eeeeeeee.[‌888‌] Meeee eeeeeeeeeee eeeee eeee eeeeeeeeeeeee- ee eeee ee eeee eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee ee [8+8] eeeeeee eee eeee eee eeeeeeeeeeeee 8-eeeeeeeeeeeeee-8-eee ‌888‌ eee eeeeeeeeee-8,8-eeeee ‌888‌, eeeeeeeeeeee, ee eeee eeeeee. Me eee eeee ee eee eeeeeeeeeeeeee, eee eeeeeeeeeee ‌888‌, eeeee eeeeee eeee ‌888‌ ee eeeeeeee eeee e eeeeee eeeeeeee ee eeeeeeeeee, eee eeee eeee eeeeeeee.

‌Meeeee 888‌ [8+8]-Meeeeeeeeeeee Meeeeeeee ee Meeee Meeeeeeeeee[‌888‌,‌888‌–‌888‌]

Meeeeeeeeeee Meeeeeeee

8-Meeeee-8-eeeeeee-8-eeeeeeeeeee-8,8,8,8-eeeeeeeeeeeeeeeeee-8(8M)-eee (‌888‌); Meeeeee Meeeeeeee:[‌888‌]

8-Meeeeeeeeeeeeeeeeeeee eeeeeeeeee (‌888‌), eeeeeeee ee Meeeeee eeeeeeeeeeeee eeee eee eeeeeeeeeeeee eeeeeeeeeeeeeee eeee (8.88 e, 8.88 eeee), eee eee eeeeeeee eee eeee ee e eeee ee eee eeeeeee (88 eM). Meee eeee eee eeeeee ee 8°M eee eeeeee eeeee eeeeeeeeeeee [eeeeeeee eeee eeeee eeeeeeeeeeee (8.88 e, 8.88 eeee) eee e 88% eeeeeeeeee ee MeM ee eee (8.88 ee, 8.88 eeee)] ee eeeeeee (88 eM) ee 8°M eee eeeee. Mee eeeeeee eee eeeeeee ee eeee ee ee eeee 88 eee eee eeee eeeeeeee eeee e eee. ee MM8Me eeee, eeeeeeeee eeee Me8M (8 × 88 eM), eeeeee eeee eeeee (8 × 88 eM), eee eeeee (Me8MM8). Mee eeeeeee eee eeeeeee eeeee eeeeeee eeeeeeee ee eeee eee eeeeeeeeeeee eeeeee, eeeee eee eeeeeeeee ee Me8M (88 eM). Meee eeee eee eeeeeeee ee e eeeeeeee eee eeee eeeeeeeee ee 888°M, eeeeeeeeee ee eeee eeeeeeeeeee eee 8–8 e, eee eeee eee eeeee eee eeeeeee eeee eee eeee eee eeeeeee ee eeee. Mee eeeeeee eeeeeeeeeeee ee eeeeeee; eeeee: 8.88 e (eeeeeeeeeee eeeee: 88%; eeeeeee eeeee eeee eeeee eeee: 88%); ee 888.8–888.8°M.

References

Meeeeee Meeeeeeeeee

• 8.Meeeee-Meee, (8888) 8/8e, 8888.
• 8.Meeeee-Meee, (8888) M 8, 888.
• 8.Meeeee-Meee, (8888) M 8, 888.
• 8.Meeeee-Meee, (8888) M 88e8, 888.