Navigation

0 Hits

  • Previous / Next

You are using Science Of Synthesis as a Guest.
Please login or sign up for a free trial to access the full content.
9.9.1.3.1.1.6 Method 6: Cyclization of Alkane-1,4-diones (The Paal–Knorr Synthesis)

DOI: 10.1055/sos-SD-009-00244

König, B.Science of Synthesis, (20019207.

The acid-catalyzed cyclization of alkane-1,4-diones 118 followed by elimination of water to furans 119, known as the PaalKnorr synthesis,[‌196‌‌198‌] is a procedure of general applicability (Scheme 40).[‌199‌‌205‌] Bis(epoxides) have been used as starting materials.[‌206‌] A variety of catalysts have been used: sulfuric acid,[‌207‌,‌208‌] hydrochloric acid, polyphosphoric acid,[‌209‌] 4-toluenesulfonic acid, oxalic acid,[‌210‌] ion-exchange resins, such as Amberlyst 15,[‌211‌] and acetic anhydride/zinc bromide.

Meeeee 88 Mee MeeeMeeee Meeeee[‌888‌‌888‌]

Meeeeeeeeee 88

M8 M8 M8 M8 Meee Meeee (%) ee 888 Mee
Me M M Me Meeeeeeee 88 >88 [‌888‌]
Me Me Me Me Meeeeeeee 88 88 [‌888‌]
Me MM8M M Me (MM8M)8 88 [‌888‌]
Me M M Me MMe 8888 [‌888‌‌888‌]
Me MM8 MM8 Me M8MM8 88 [‌888‌]
e-Me M M e-Me M8MM8 88 [‌888‌]
Me Me Me Me M8MM8 88 [‌888‌]
Me M Me Me M8MM8 88 [‌888‌]
Me 8-MeMM8M8MM8 8-MeMM8M8MM8 Me M8MM8 88 [‌888‌]
8-M8MM8M8 MM8Me MM8Me Me M8MM8 88 [‌888‌]
Me M M Me MMM 88 [‌888‌]
8-MeM8M8 M M 8-MeM8M8 MMM 88 [‌888‌]
8-MeMM8M8 M M 8-MeMM8M8 MMM 88 [‌888‌]
8-M8MM8M8 M M 8-M8MM8M8 MMM 88 [‌888‌]

Meeeeeeeeeee Meeeeeeee

8,8,8,8-Meeeeeeeeeeeeeee (888, M8=M8=M8=M8=Me); Meeeeee Meeeeeeee:[‌888‌]

M eeeeeee ee 8,8-eeeeeeeeeeeeee-8,8-eeeee (8.88e, 88.8eeee) eee Meeeeeeee 88 eee-eeeeeeee eeeee (8.8e) ee eee eeeeeee (88eM) eee eeeeeeee ee e MeeeMeeee eeee eee 8e. Mee eeee eee eeeeeeee, eee eeeeeee eeeeeeeeee, eee eee eeeeeee eeeeeeeeeeee ee eeee 8,8,8,8-eeeeeeeeeeeeeeee; eeeee: 8.88e (88%); ee 8888°M/8.8Me.

8,8-Meeeeeeeeeeee (888, M8=M8=Me; M8=M8=M); Meeeeee Meeeeeeee:[‌888‌]

M eeeeeee ee 8,8-eeeeeeeeeeeeee-8,8-eeeee (8.8e, 8.8eeee) eee MMM (888e) eee eeeeee ee 888888°M eee 88eee. Mee eeeeeee eee eeeeee eeee eee (888e) eee eee eeeeeeeeeee eee eeeeeeeee ee eeeeeeeeee. Mee eeeee eeeeeee eee eeeeeeee ee eeeeeeeeeee ee eeee 8,8-eeeeeeeeeeeee; eeeee: 8.88e (88%); ee 8888°M.

References