Science of Synthesis

Schatz, J., Science of Synthesis, (2001) 9, 371.

Coupling of halogenated thiophenes in the presence of copper metal gives rise to bithiophene derivatives in low to moderate yields (Ullmann reaction).[‌880‌–‌883‌] High-boiling solvents such as dimethylformamide, nitrobenzene, or quinoline are used. Reductive replacement of halogen by hydrogen atoms is a possible side reaction (cf. Section ‌9.10.1.4.4.1‌). Therefore, the formation of thienylcopper compounds by the reaction of bromo- or iodothiophenes with copper(I) salts prior to the coupling with other (het)aryl halides is advantageous (‌Scheme 104‌).[‌884‌–‌891‌] The addition of copper(I) thiophene-2-carboxylate (‌259‌) promotes the cross coupling of 2-iodothiophene to give ‌260‌ to such an extent that the reaction can be performed at room temperature (‌Scheme 105‌).[‌892‌] Reaction of 2-thienyllithium with copper(I) cyanide in a ratio of 1:1 gives rise to the lower-order cuprates (2-thienyl)(CN)CuLi as precursors for mixed cuprates; the reaction in a 1:2 ratio yields the cuprates (2-thienyl)2CuLi·LiCN.[‌893‌–‌895‌] While organocuprates in general have been applied successfully in various C—C bond-forming reactions (e.g., conjugate addition, acylation, and alkylation of the organic ligand), the latter thienylcuprates have not yet found widespread use. This is probably due to the fact that in mixed cuprates of the type RT(2-thienyl)CuLi, in which RT represents a transferable ligand, the thiophene ring accepts the role of a dummy ligand.[‌896‌] However, homocuprates such as (2-thienyl)2CuLi and (2-thienyl)2CuLi·LiCN (‌261‌), prepared from 2-thienyllithium and a copper(I) halide or copper(I) cyanide in a 2:1 ratio, do undergo coupling reactions to give arylthiophenes ‌258‌ (‌Scheme 104‌) and conjugate addition to propyniminium salts ‌262‌ to give allenylthiophenes ‌263‌ (‌Scheme 106‌).[‌897‌,‌898‌]

Mee eeeeeeee ee eeeeeeeeeee eeeeeeee ‌888‌, eeeeeeee ee eeee eeee eee eeeeeeeeeeeee eeeeeeeeeeeeee eeeeeeee, eeee eeee(MM) eeeeeeee eeeeeeee ee e eeeeeeeee-eeeeeeee eeeee-eeeeeeee eeeeeeee eeee eeee eeeeeee eeeee eee eeeeeeeeeeeee eeeeeeeeeeeee ‌888‌ (‌Meeeee 888‌).[‌888‌,‌888‌–‌888‌] Meee eeeeee eeeeee eeee e eeeeeeeeee eee eeeeeeeee eeeeeeeee ee eeeee eeee–eeeeeee eeeeeeeee eee eeee eeeeeeee.[‌888‌,‌888‌–‌888‌]

‌Meeeee 888‌ Meeeeeee ee Meeeeeeeee eee Meeeeeeeeeee Meeeeeeeeee[‌888‌]

‌Meeeeeeeeee 888‌

‌Meeeee 888‌ 8,8′-Meeeeeeeeee ee Meeeeee-Meee Meeeeeeee Meeeeeee[‌888‌]

‌Meeeee 888‌ Meeeeeeee Meeeeeee ee Meeeeeeeeeeeeee ee Meeeeeeeeeeee Meeee[‌888‌]

‌Meeeee 888‌ Meeeeeeee-Meeeeeeee Meeee Meeeeeee ee Meeeeeeeeee Meeeeeee[‌888‌]

‌Meeeeeeeeee 888‌

Meeeeeeeeeee Meeeeeeee

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

M eeee ee 8-eeeeeeeeeeeeee (888 eeee), eeeeeeee eeee eeeeeeeee eee MeMe, ee Me8M (88 eM) eee eeeee ee ee eee-eeeeee eeeeeeeeee ee MeM (88.88 e, 888 eeee) ee Me8M eee eee eeeeeee eee 88 eee; e eeeeeeeee eeeeeeeeeee eeeeee. Meeeeeeeeee (88.8 e, 888 eeee) eee eeeeeeeee (88.8 e, 888 eeee) eeee eeeee eee eee eeeeeee eee eeeeee eeee eeeeeeee, eee Me8M eeeee eeeeeeeee eee, ee 888°M eee eeee ee eeee eeeeeeeeeee eee 88 eee. Mee eeeeeee eee eeeeeeeee ee eeeee ee eeee eee eeeeeee; eeeee: 8.88 e (88%); ee 888–888°M/88 Meee; ee 88–88°M.

8,8′-Meeeeeeeeee (‌888‌):[‌888‌]

Meeeee(M) eeeeeeeee-8-eeeeeeeeeee (‌888‌; 8.88 e, 8.8 eeee) eee eeeee ee eee eeeeeee ee 8-eeeeeeeeeeeee (888 ee, 8.8 eeee) ee MMM (8 eM) eeeee ee eeeee eeeeeeeeee. Meeee eeeeeeee ee ee eee 88 e, eee eeeeeee eee eeeeeee eeee MeMMe (88 eM), eee eee eeeeeeeee eeeeeee eee eeeeee eeeeeee e eeee ee eeeeee eee eeeee MeMMe ee eeeeee (888 eM); eee eeeeeeee eeee eeeeeee ee eeeee eeeeeeeee ee ee. Mee eeeee eeeeeee eee eeeeeeeee ee MM8Me8 (8 eM) eee Me8M (88 eM), eee eeeeee ee eee eeeeeeee eee eeeeeee, eee eeeeee eee eeeee ee eeeeeeeeeee eee eeeeeee eeeee eeeeeee ee eee eeeeeee ee eeee ‌888‌; eeeee: 888 ee (88%).

Meeeeee Mee(8-eeeeeee)eeeeeee–Meeeeee Meeeeee (‌888‌):[‌888‌]

Meeeeeeee (8.88 eM, 888 ee, 88.8 eeee) eee eeeee ee MMM (88 eM) ee e 88-eM, eee-eeeeee eeee-eeeeee eeeee ee −88°M, eeeeeeee ee 8.88 M MeMe ee eeeeee (8.8 eM, 88.8 eeee). Meeeeeee eee eeeeeeeee eee 88 eee, eeee ee −88°M eee 88 eee. Mee eeee eee eeeeeeeeeee eee e eeeeee-eeeee eeeeee eeee e eeeeee ee MeMM (888 ee, 88.8 eeee) eee MMM (88 eM), eeee e eeee ee MMM (88 eM). Meeeeee ee 88°M eeee e eeeee, eeeee-eee eeee eeeee eee eeeeeee eeee MMM (88 eM) eee eeee eeeeeeeeeee eee eeeeee-eeeee eeeeee eeee e eee eeeeeee eeeeee, eeeee eee eeeeeeeeee eeeee e eeeeeeee eeeee eeeeeeee.

8-Meeeeeeeeee Meeeeeee (‌888‌):[‌888‌]

Me e eeeeeee eeee ee eee MeMe8 (88.8 e, 888 eeee) ee MMM (888 eM), ee ee eeeee ee eeeee eeeeeeeeee, eee eeeee e eeee ee 8-eeeeeeeeeeeeee (888 eeee) (ee. Meeeeee ‌8.88.8.8.8.8.8‌) ee MMM (888 eM) eee eeeeee-eeeee eeeeee. Mee eeeeeeeee eeeeeee eee eeeeeee ee ee eee 8 e eee eeee eeee eeeeeeeeeee eee eeeeeee eeeeeeeee.

8-Meeeeeeeeeeeeee (‌888‌, Me8 = Me); Meeeeee Meeeeeeee:[‌888‌]

M eeee ee 8-eeeeeeeeeee eeeeeeee (‌888‌; 888 eeee) ee MMM (888 eM) eee eeeee eeeee e eeeeee-eeeee eeeeee ee e eeeeeee eeeeeee ee MeMe (88.8 e, 888 eeee) eee (Me8M)8Me (8.88 e, 8.88 eeee) ee MMM (888 eM) eeeee ee eeeee eeeeeeeeee. Mee eeeeeee eee eeeeeee ee 88°M eee 88 e, eeee eeeeee eee eeeeeeee eeee ee 8 M MMe (888 eM). Mee eeeeeee eeeee eee eeeeeeeee eeee Me8M (8 × 888 eM), eeeee (MeMM8), eeeeeeee, eee eee eeeeeee eeeeeeeeee ee eeee e eeeeee-eeeee eee. Meeeeeeeeeee ee eeeee eeee 8-eeeeeeeeeeeeeee ee e eeeee eeeeeeeeeee eeeee; eeeee: 88.8 e (88%); ee 88–88°M.

References

Meeeeee Meeeeeeeeee

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