Science of Synthesis

Smith, K. M.; Vicente, M. G. H., Science of Synthesis, (2004) 17, 1096.

The most efficient method for the synthesis of unsymmetrical dipyrroketones (e.g., ‌68‌, R1 = O) involves a modification of the Vilsmeier–Haack reaction. Condensation of the phosphoryl chloride complex of a pyrrole N,N-dimethylcarboxamide ‌67‌ with a nucleophilic 2-unsubstituted 1H-pyrrole (e.g., ‌34‌) followed by hydrolysis of the intermediate imine salt ‌68‌ (R1 = NMe2+Cl−) gives the dipyrroketone ‌68‌ (R1 = O) in very good yield (‌Scheme 17‌).[‌53‌] Alternatively, treatment of a pyrrole acid chloride ‌69‌ with a pyrrole Gri­gnard derivative ‌70‌ (or with the 2-unsubstituted 1H-pyrrole in the presence of a Friedel–Crafts catalyst) gives dipyrroketones ‌71‌[‌53‌,‌54‌] (‌Scheme 17‌).

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Meeeeeeee ee eeeeeeeeeeeeeee (e.e., ‌88‌) eeee eeee(MM) eeeee, eeee(MM) eeeeeee,[‌88‌] eeeeeeee eeeeeeee, ee eeeeeee/eeeeeeee eeeeeeee[‌88‌] eeee eeeee eeee eeeeee ee eeeeeeeeeeeeee ‌88‌. Meeeeeeee ee eeeeeeeeeeeeee ‌88‌ eeee eeeeee eeeeeee[‌88‌] ee eeeeeeee eeeeee eee eeeeeeeeeeeee eeeeeeeeeeeeeee ‌88‌.

‌Meeeee 88‌ Meeeeeeeeeeee Meeeeeeee[‌88‌–‌88‌]

Meeeeeeeeeee Meeeeeeeee

Meeeee 8,8-Meeeeee-8,8,8-eeeeeeeee-8-eeeeeeeeeeeee-8-eeeeeeeeeee (‌88‌, M8 = M); Meeeeee Meeeeeeee:[‌88‌]

Meeeee 8-[(eeeeeeeeeeeee)eeeeeeee]-8-eeeee-8-eeeeee-8M-eeeeeee-8-eeeeeeeeeee (‌88‌; 88 e, 88.88 eeee) eee eeeeeeeee ee MMMe8 (88 eM) eee eeeeeee eeeee eee eeeeeeeeee ee 888 ee eee eeeeeeeee (ε 88,888). Mee eeeeee ee MMMe8 eee eeeeeee ee eeeeeeeeeeeee eeeee eeeeeee eeeeeeee, eeee 8,8-eeeeeeeeeeeee (88 eM) eee eeeee eee eee eeee eeeeeeeeeeee ee eeeeee eee eeee eeeeee ee MMMe8. Mee eeee eeeeeee eee eeeeeeeee ee MM8Me8 (88 eM) eee 8-eeeee-8,8-eeeeeeee-8M-eeeeeee (‌88‌; 8.88 e, 88.88 eeee) ee MM8Me8 (88 eM) eee eeeee. Meeee eeeeeeee eeeee eee eeeeeeeeee ee 888 ee eee eeeeeeeee (ε 8888), MeMMe (88 e) ee M8M (888 eM) eee eeeee eee eee eeeeeee eee eeeeeeee eeee eeeeeeee eeeeeeee eee 8 e. Mee eeeeeee eee eeeeee, eee eeeeeee eeeee eee eeeeeeeee, eee eee eeeeeee eeeee eee eeeeeeeee eeee MMMe8. Mee eeeeeeee eeeeeee eeeeee eeee eeeeee eeee ee Me8MM8 (88%) eee M8M, eeeee (MeMM8), eee eeeeeeeeeeee ee eeeeeee. Mee eeee eee eeeeeeeeeeee eeee eeeeeeeeee eeee MeMM, eee eee eeeeeee eee eeeeeeeeeeeeee (MMMe8/eeeeeeeee eeeee) ee eeee eee eeeeeee; eeeee: 8.8 e (88%); ee 888°M.

8,8,8,8,8,8-Meeeeeeeee-8-eeeeeeeeeeeee (‌88‌); Meeeeee Meeeeeeee:[‌88‌]

MMMMMMM: Meeeeeeeeeee ee e eeeeee eeeeeeeeeee eeeeeeee eee eeee eeeee ee eeeeeeeeee.

M eeeeeee eeee ee 8,8,8-eeeeeeeee-8M-eeeeeee (‌88‌; 8.8 e, 88.8 eeee) ee Me8M (888 eM) eee eeeeeee eeeeeeee ee 8°M eeee e eeee ee eeeeeeeeeeee (8.88 eM) ee eeeeeee (88 eM) (MMMMMMM: eeeeeeeeee). Mee eeeeeee eee eeeeeee eee 88 eee eeeeee eeeeeeee ee ee MeMM (88%, 888 eM) eee eeeeeeee eee eeeeeee 88 eee ee ee. Mee eeeeeee eee eeeeeeeeeeee ee eeee e eeeeeeeeeee eeeeeee, eeeee eee eeeeeeeeeeeeee (ee MeMM) ee eeee eee eeeeeeeeeeeee ‌88‌; eeeee: 8.8 e (88%); ee 888–888°M. Mee eeeeee ‌88‌ (88 ee, 8.88 eeee) ee MeMM (88%, 88 eM) eeeeeeeeee MMM (8.8 e) eee eeeeeee eeee ee M8M8 (8%, 8 eM) eee eeee eeeeee ee e eeeee eeee eee 8 eee. M8M (88 eM) eee eeeee eee eee eeeeeee eee eeeeeeeee eeee MMMe8 (8 × 8 eM). Meeeeeeeeee ee eee eeeeeee eeee e eeeeeee, eeeee eee eeeeeeee ee eeeeeeeeeee (888°M/8 Meee) ee eeee eee eeeeeeeeeeeee ‌88‌; eeeee: 88 ee (88%); ee 888–888°M.

Meeeeee 8,8-Mee[8-(eeeeeeeeeeeeee)eeeee]-8,8-eee[(eeeeeeeeeeeeee)eeeeee]-8-eeeeeeeeeeeee-8,8-eeeeeeeeeeeee (‌88‌); Meeeeee Meeeeeeee:[‌88‌]

M eeee ee eeeeeee 8,8-eee[8-(eeeeeeeeeeeeee)eeeee]-8,8-eee[(eeeeeeeeeeeeee)eeeeee]eeeeeeeeeeeeee-8,8-eeeeeeeeeeeee (‌88‌; 8.8 e, 8.88 eeee) ee MeMM (88 eM) eee eeeeeee eeee Me(MMe)8 (8.8 e, 8.88 eeee) eee eeeeeee ee ee eee 8 e. MeM8 (88%, 8.8 e, 8.88 eeee) eee eeee eeeee eee eeeeeeee eee eeeeeeeee eee eeeeeee 8 e. Mee eeeeeee eee eeeeeeeeeee eee eee eeeeeeeeeee eee eeeeee eeee eee eeeee (888 eM). Mee eeeeeeeee eeeeeeeeeee eee eeeeeeeee, eeeeee eeee M8M, eeeeeeeee ee Me8M, eee eeee eeeeee eeeeeeeeeeee eeee M8M, 8% ee MeMMM8, eee M8M, eee eeee eeeee (Me8MM8). Meeee eeeeeeeeeeeee, eeeeeeee eeeeeeeee; eeeee eeee eeee eeeeeeeeeeeeee (Me8M) ee eeee ‌88‌; eeeee: 8.88 e (88%); ee 888.8–888.8°M.

Meeeeee 8,8-Mee[8-(eeeeeeeeeeeeee)eeeee]-8,8-eee(eeeeeeeeeeeeeeeeeeee)eeeeeeeeeeeeee-8,8-eeeeeeeeeeeee (‌88‌); Meeeeee Meeeeeeee:[‌88‌]

Meeeeee 8,8-eee[8-(eeeeeeeeeeeeee)eeeee]-8,8-eee(eeeeeeeeeeeeeeeeeeee)-8-eeeeeeeeeeeee-8,8-eeeeeeeeeeeee (‌88‌; 888 ee, 8.88 eeee) ee MeMM (8 eM) eee eeeee ee M8M (8 eM) eee eeeee MMe (8 eM) eee Me eeeeeee (888 ee). Mee eeeeeee eee eeeeeeee eee 8 e, eeeeee, eee eeee eeeeeeee. Mee eeee eee eeeeeeeeeeee eee eeee eeeeeeeeeeee ee eeee eeeeeeee ee eee eeeeeeeeeeeeee ‌88‌; eeeee: 888 ee (88%), ee 88°M.

References