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.
16.14.4.1.2 Of Metals

DOI: 10.1055/sos-SD-016-00919

Sato, N.Science of Synthesis, (200416797.

The most important organometallic forms of electron-deficient heteroaromatics are the organolithium compounds; the formation of these in the pyrazine series is discussed in Section 16.14.4.1.1.2. Pyrazinyllithium complexes react with a variety of reagents, therefore they are versatile intermediates for the synthesis of otherwise inaccessible pyrazine derivatives 188 (Scheme 66). The exchange of ring hydrogen with deuterium is realized by quenching of the lithiated pyrazines 139 with deuterated solvent (Scheme 41, Section 16.14.4.1.1.2). Pyrazinyllithiums 139 undergo transmetalation with zinc(II) chloride[‌303‌] or tributyltin chloride.[‌226‌,‌233‌] The organozinc compounds couple with iodobenzene in the presence of tetrakis(triphenylphosphine)palladium(0) to afford phenylpyrazines; cross-coupling is often improved by sonication. (Trimethylsilyl)pyrazines are generated by simultaneous addition of metalating agent and chlorotrimethylsilane to a solution of the substrate.[‌222‌,‌226‌,‌227‌,‌231‌,‌233‌] Electrophilic substitution on pyrazinyllithiums 139 provides a variety of pyrazine derivatives (Scheme 66), for example methylpyrazines,[‌227‌,‌233‌] (trifluoromethyl)pyrazines,[‌304‌] pyrazinemethanol derivatives,[‌222‌,‌226‌,‌227‌,‌229‌,‌231‌,‌233‌‌235‌] pyrazinecarbaldehydes,[‌222‌,‌223‌,‌226‌,‌227‌] acylpyrazines,[‌223‌,‌226‌,‌227‌] and pyrazinecarboxylic acids.[‌222‌,‌227‌] In addition, heteroatom functionalities can be similarly introduced, for example chloropyrazines are prepared by treatment of pyrazinyllithiums 139 with hexachloroethane,[‌226‌,‌233‌] and iodopyrazines are similarly synthesized with iodine.[‌223‌,‌226‌,‌227‌,‌233‌,‌235‌] (Phenylsulfanyl)pyrazines are obtained by treatment of pyrazinyllithiums 139 with diphenyl disulfide.[‌226‌,‌227‌,‌233‌] When tosyl azide is used as the electrophile, azidopyrazine is produced.[‌228‌] Grignard derivatives of pyrazines can be prepared (Section 16.14.4.1.4.2) and coupled with an aldehyde to afford low to moderate yields of pyrazinemethanol derivatives.[‌305‌]

Meeeee 88 Meeeeeeeeeeee Meeeeeeeeeee ee Meeeeeeeeeeeeeee Meeeeeeee[‌888‌,‌888‌,‌888‌,‌888‌,‌888‌,‌888‌]

Meeeeeeeeee 88

M8 M8 M8 Meee (°M) Meeeeeeeeeee Meeee (%) Mee
M M Me 88 MeM 88 [‌888‌]
MMe M MM(MM)Me 88 MeMMM 88 [‌888‌]
Me M M(MM)Me8 88 Me8MM 88 [‌888‌]
M M MMM 88 MMM8Me 88 [‌888‌]
M M Me 88 MeMMe8 88 [‌888‌]
Me M MM8M 88 MM8 88 [‌888‌]
M MMMMe-Me Me 88 M8Me8 88 [‌888‌]
M M M 88 M8 88 [‌888‌]
M M MMe 88 MeMMMe 88 [‌888‌]
MMe M M8 88 MeM8 88 [‌888‌]

Meeeeeee M-eeeeee 888 eeee eeeeeee eeeeeeeeee eee eeeeeeeeee eeeeeeeeeeeee eeeeeeeeeeee ee eeeeeee e eeeeee ee eeeeeeee eeeeeeeeeee 888 (Meeeee 88).[‌888‌] Meeeee eeeeeeeeeeeee ee eeeeeeee M-eeeeee eee eeee eeeeeeeee ee eeeeeeeee eeee eeeeee ee eee eeeeeeee ee eeeeeee eeeeeeeeeeeeeeee, eee eeee eeeeee ee eee eeee eeeeeeeee eee eee eeeeeeeee ee eeeeeeeee 8-eeeeee eeeeeee ee eee eeeeee eee eee eeeeeeeee ee eeeeeeeeee.[‌888‌]

Meeeee 88 Meeeeeeeeeeee Meeeeeeeeeee ee Meeeeeeee Meeeeeee M-Meeeee[‌888‌]

Meeeeeeeeeee Meeeeeeee

8-Meeeee-8-(8-eeeeeeeeeeee)eeeeeeeee 888, [M8=Me; M8=M; M8=MM(MM)M8]; Meeeeee Meeeeeeee:[‌888‌]

M eeee ee MeMe ee eeeeee (8.8eM, 8.8eeee) eee eeeee ee eeee (88°M) eeeee MMM (88eM) eeeee eeeee eeee eeeeeeee. Mee eeeeeee eee eeeeee ee 88°M, eee MMM (8eM, 8.8eeee) eee eeeee. Mee eeee eee eeeeeee ee eeee ee ee 8°M eee eee eeee ee eeee eeeeeeeeeee eee 88eee. Meeee eee eeee eee eeeee eeee eeeeee ee 88°M, eeeeeeeeeeeeee (8.8eM, 8.8eeee) eee eeeee, eee eee eeeeeee eee eeeeeee eee 88eee ee 88°M. Mee eeeeeeeeeeee (8eeee; ee eee eeee ee eeeeeeeeeeee, 8eM, 88eeee) eee eeeee, eee eee eeeeeee eee eeeeeee eee 8.8e ee 88°M. Mee eeeeeee eee eeeeeeeee eeeeeeeeee eeee e eeeeeee ee 88% ee MMe (8eM), MeMM (8eM), eee MMM (8eM) ee 88°M, eee eeee eeeeee eeeeee ee ee. Mee eeeeeeeee eeeeeee eee eeeeeeeeeee eeee eee. MeMMM8 (88eM), eee eeeeeeeeeeee ee eeee eeeeeee. Mee eeeeeee eee eeeeeeeee eeee MM8Me8 (8×88eM). Mee eeeeeee eeeeeee eee eeeee (MeMM8) eee eeeeeeeeee. Mee eeeee eeeeeee eee eeeeeeee ee Meeeeeeee eeeeeeeeeeee ee ee eeeeee eeeeeeeeeeeeee (eeeeee eee, MM8Me8).

8-Meeee- eee 8-Meeeeeeeeeee 8-Meeeee 888; Meeeeee Meeeeeeee:[‌888‌]

M eeee ee eeeeeeee M-eeeee 888 (8eeee) ee eeeee MMM (8eM) eee eeeee ee e eeeeeee eeee ee MMMM [eeeeeeee eeee MMM (8.88eM, 8.8eeee) eee 8.8M MeMe ee eeeeee (8.88eM, 8.8eeee)] ee eeeee MMM (8eM) eeeee eeeee ee 88°M. Mee eeeeeee eee eeeeeee ee eeee eeeeeeeeeee eee 88eee, eee MMMMM (8.88eM, 8.8eeee) eee eeeee. Meeee eee eeeeeee eee eeee eeeeeee eee 88eee, e eeee ee eee eeeeeeeeeeee (8.8eeee) ee eeeee MMM (8eM) eee eeeee eeeeeeee ee 88°M, eee eee eeeeeee eee eeeeeee eee 88e, eeeeee ee 8°M, eee eeee eeeeeeeeee ee eeee eeeeeeeeeee eee 8e. Me eee eeeeeeeee eeeeeee eee eeeee eeeee 88% ee MM8Me eee eeee Me8M (88eM). Mee eeeeeee eeeee eee eeeeeeeee eeee Me8M (8×88eM), eee eeeeeeee eeeeeee eeeee eee eeeee (Me8MM8), eee eee eeeeeee eee eeeeeee ee eeeee. Mee eeeeeee eee eeeeeeee ee eeeeeeeeeeeeee.

References