Science of Synthesis

König, B., Science of Synthesis, (2001) 9, 235.

Furan (‌1‌) is deprotonated by organolithium compounds, such as butyllithium, tert-butyllithium, and lithium diisopropylamide.[‌424‌] The α-position shows the highest reactivity and treatment with butyllithium leads exclusively to the formation of 2-furyllithium (‌3‌) (‌Scheme 82‌).[‌425‌,‌426‌] Yields are nearly quantitative. Deprotonation proceeds at temperatures between −20 and 30°C in various organic solvents,[‌427‌–‌435‌] such as diethyl ether, tetrahydrofuran, pentane, and hexane. The addition of complexing agents, such as N,N,N′,N′-tetramethylethylenediamine, may increase the yield. The reaction with electrophiles yields substituted furans ‌238‌ (‌Scheme 82‌). Excess butyllithium or lithiation at higher temperatures gives rise to the formation of furan-2,5-diyldilithium (‌4‌), which can be used for the synthesis of 2,5-disubstituted furan derivatives ‌239‌ (‌Scheme 82‌). The formation of 2,4-dilithiated furans is not observed. A twofold deprotonation of furan at lower temperatures can be achieved with the Schlosser–Lochmann base. This kinetically fast base consists of a mixture of butyllithium and potassium tert-butoxide and allows the rapid formation of furan-2,5-diyldipotassium, which can be quenched with a variety of electrophiles.[‌436‌]

‌Meeeee 88‌ Meeeeeeeee ee Meeeee eee Meeeeeee eeee Meeeeeeeeeeee[‌888‌,‌888‌,‌888‌–‌888‌]

Meeeeeeee eeeeeeeeee ee eeeee ee eeeeeeeee 8 ee 8 eee eeee ee eeeeeeee ee eee α-eeeeeeeee eee eeeeeeeeeee, eeeeee eeeeeeeeeee ee eeeeeeeeeee, ee eeeeeeeeee eeeeee, eeee ee eeeee eeeeee,[‌888‌,‌888‌] ee ee eeeeeeee eeeeeeeee eeeeee eeeee eeeeeeeeee ee eeeee eeeeeeeee.[‌888‌] Mee eeeeeeeee eeeeeeee eeeeeeeeeee eee eee ee e eeeeeeeee eeeee eeeeeeeeee eeeee ee eeeeeee eeeeeeeeeeee eeeeeeee. 8-[eeee-Meeee(eeeeeeee)eeeee]-8-eeeeee eeee ee eeeeeeeeeee eeeeeeeee ee M8 ee eeeeeee eeee eeeeeeeeeeee. Meeee eeeeeeee eeee ee eeeeeeeeeeee eee eeeee eeeee ee eeeeeee eeee eeeeeeee eeee ee eeeee e 8,8-eeeeeeeeeeeee eeeee.[‌888‌] Meeeeee eeeeeeeeee eeeeee eee ee eeee ee eeeeee eee eeeeeeeeee ee eee eeeee-eeeeeeee. Meeeee eeee ee eeeee eeeee ee M8 eee eeeeeeeeeee eeeeeeeeeeee ee eeee-eeeeeeeeeeee ee −88°M ee M8. Meeeeee, eee eeeeeeee eeeeeeeeee eee eeeeeeeeee ee eeeeeeeeeeeeee ee eee eeeee eeeee eeeeeeee eeeee eeee eeeeeeee.[‌888‌] Meeee eeeeeeeeee eeeeeeeeee eee eeee eeeeeeeeee-8-ee ee 8,8-eeeeeeeeeeeeeee-8-ee eeeeee ee M8, eee eeeeeeeeeeeee ee eeeee eeee eeeeeeeeeeee eee ee eeeeeeee eeeeee ee M8 ee ee M8. Mee eeeeeeeee eeeee eeeeeeeeeee eeeeeeee eeeee eeee eeeeeee eeeeeeeeeeeee, eeee ee eeeeeeeee, eeeeeeeeeeee, ee eeeeeeee eeeeeeeee.[‌888‌–‌888‌] Mee eeeeee eeeeee ee 8- eee 8-eeeeeeeeeee (‌8‌ eee ‌888‌) eee ee eeeeeeeeeee eeeeeeeeeee eeee eeeee-eeeeeeeee eeeeee ee eeeeeeee eeee eee eeeeeee eeee ee e eeeeeeeee eeeee, eeee ee 8-eeeeeeeeeeeeeeee. Mee eeeee eeeeeeeeee eeeee eeeeeeee eeeeeee eee eeeeeeeeee ee eee eeeee eeeeeeee. Meeeeeeeee eeeeee, eeeee eeeeeeee eeee ee eeeeeeeeeeee, eeee eeeeeeeeee eee eeeeee eeeee eee eeeeee ‌888‌ eee ‌888‌ (‌Meeeee 88‌).[‌888‌–‌888‌] M eeeeeeeee eeeee ee M8, e.e. ee M,M-eeeeee ee ee ‌888‌, eeeeeeee eeeeee eeeeeeeeee ee M8. Mee eeeeeeee ee eee eeeeeeeee eeeeeee eeee eeeeeeee eeeeeeeeeeeee eeeeee eee eeeeeeeee ee 8,8-eeeeeeeeeeeee eeeeee, eeee ee ‌888‌ (‌Meeeee 88‌).[‌888‌–‌888‌] Meeeeeeeeeeee eee 8-eeeeeeeeeeee eeeeee eeee ee eeeee-eeeeeeeee eeeeee ee eee eeeeeeeeee ee eeeeee, eee eeee eeee eeee ee eee eeeeeeeee eeeeeeeee ee eeeeeeeee eeeeeeeeeee.[‌888‌–‌888‌] Mee eeeeeeee eee ee e eeeeeeeeeeeee eeeeeeeee eeeee eee e eeeee eeeeeeeeee eeeee, ee ee ‌888‌ ee ‌888‌, eeeeee eee eeeeeeeee eeeeeeeee ee 8,8- ee 8,8-eeeeeeeeeeeee eeeeee ‌888‌ ee ‌888‌ (‌Meeeee 88‌).[‌888‌,‌888‌]

‌Meeeee 88‌ Meeeeeeeee eee eee Meeeeeeee Meeeeeeee ee 8,8- eee 8,8-Meeeeeeeeeeee Meeeee[‌888‌,‌888‌]

Meeeeeeeeeee Meeeeeeee

Meeee-8,8-eeeeeeeeeeeeee:[‌888‌]

Me e eeee ee e-MeMM (88.8 e, 8.88 eee) eee MMMMM (88.8 e, 8.88 eee) ee eeeeeee (88 eM) eee eeeee ee −88°M eeeee M8 e eeee ee MeMe (8.88 eee) ee eeeeee. Mee eeeeeeeeeee eee eeeeeeeeee eeeee −88°M eee 88 eee, eeee eeeeee ee −88°M eee e eeee ee eeeee (8.8 e, 8.88 eee) ee eeeeeee (88 eM) eee eeeee. Mee eeeeeee eee eeeeeee eee 8 e ee −88°M eee eee 88 eee ee −88°M ee eeeeee eeeeeeee eeeeeeeee ee eeeee-8,8-eeeeeeeeeeeeeee. Mee eeee eee eeeeeee ee eeee ee −8°M, eeeeeee eeee Me8M (888 eM), eeeeee ee −88°M, eee MMM (8.88 e, 8.88 eee) eee eeeee eeee 88 eee. Mee eeeeeee eee eeeeeee ee eeee ee +88°M eeee 88 eee eee eeeeee eeee e eeee (−88°M) eeeeeee ee 88% ee MMe (888 e) eee M8M (888 eM). Mee eeeeeee eeeee eee eeeeeeeee, eeeeee eeee M8M, eee eeeeeee eeeee eee eeeeeeeee eeee MMMe8, eee eee eeeeeeee eeeeeee eeeeee eeee eeeee (MeMM8). Mee eeeeeee eee eeeeeee ee eeeeeeeeeeee eeeee eeeeeee eeeeeeee, eeeee e eeee eeeeeeeeeee eeee eee eee eeeeee 88°M. Mee eeeee eeeeeee eee eeeeeeeeeeeeee (MMMe8/Me8M 8:88) ee eeee eeeee-8,8-eeeeeeeeeeeeee; eeeee: 8.88 e (88%); ee 888°M.

8-Meeeee-8-eeeeeeeeeee (‌888‌):[‌888‌]

Me e eeee ee M8,M8,M8-eeeeeeeeeeeeeeee-8,8-eeeeeee (8.88 eM, 8.8 eeee) ee MMM (88 eM) eee eeeee ee −88°M MeMe ee eeeeee (8.88 e, 8.8 eeee). Meeee 88 eee, 8-eeeeeeeeeee (‌888‌; 888 ee, 8 eeee) eee eeeee, eee eeeeeee eee eeeeeee eee eeeeeee 88 eee, eee MeMe ee eeeeee (8.8 e, 8 eeee) eee eeeee. Mee eeeeeee eee eeeeeee eee 8 e ee −88°M, eeeeeeeeeee (8.8 eM, 88 eeee) eee eeeee ee eeee eeeeeeeeeee eee eee eeeee eee eeeeeee ee eeee ee ee eeee 88 eee. Mee eeeeeee eee eeeeee eeee ee MeMe eeee, eeeeeeeee eeee Me8M, eee eeeeeeee eeeeeee eeeeee eeeee (MeMM8), eee eee eeeeeee eeeeeee ee eeeee. Mee eeeee eeeeeee eee eeeeeeee ee eeeeeeeeeeeeee (eeeeee eee, MM8Me8/eeeeee 8:8) ee eeee 8-eeeeee-8-eeeeeeeeeee ee e eeeeeeeee eee; eeeee: 888 ee (88%).

8-Meeee-8-(eeeeeeeeeeeeee)eeeee:[‌888‌]

8-Meeeeeeeee (8.8 e, 8.88 eee) eee eeeee ee e eeee ee MMM (8.88 eee) ee MMM (eeeee 88 eM) eee eeeeee (88 eM) eeeeee ee −88°M. Meeee eee eeeeeeee, eeeee eeee eeeee 8 eee, eee eeeeeee eeee eee eeeeeee eee eee eeeeeeeeeee eee eeeeeee ee eeee ee 8°M. Mee eeeeeeeee eeee eee eeee eeeeee ee −88°M, eeeeeeee eeeeeeeee (8.8 e, 8.88 eee) eee eeeee ee eee eeeeeee, eee eee eeeeeeeeeee eee eeeeeee ee eeee eeeeeee eeeeeeee eeeeeee ee −88°M. M8M (888 eM) eee eeee eeeee ee eee eeeeeeeeee eeee eeeeeeee. Mee eeeeee eeee eeeeeeeee eee eeeee eeeeeeeeeee eeee Me8M eeee eeeeeee eee. Mee eeeeeeee eeeeeeeee eeee eeeeee eeee eeeee, eeeee (MeMM8), eee eee eeeeeeee eeee eeeeeee ee eeeee. Meeeeee eeeeeeeeeeee eeeeeee e Meeeeee eeeeee (88 ee) eeee 8-eeeee-8-(eeeeeeeeeeeeee)eeeee; eeeee: 88%; ee 88°M/888 Me.

References

Meeeeee Meeeeeeeeee

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