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Sato, N., Science of Synthesis, (2004) 16, 815.
The most important reaction in this section is certainly halogenation of pyrazinols, because pyrazinols are readily prepared from aliphatic components, and, additionally, halopyrazines are versatile intermediates for the synthesis of less accessible pyrazines. Chloropyrazines 165 are generally synthesized by treatment of pyrazinol 55 with phosphoryl chloride at reflux or at elevated temperature in a sealed vessel (Scheme 95),[42,126–128,132,286,287,359,385] in which a trace of sulfuric acid or hydrochloric acid is sometimes added. Several pyrazine-2,3-diols are likewise chlorinated to afford 2,3-dichloropyrazines.[179,284] The chlorination is occasionally effected by addition of phosphorus pentachloride to the phosphoryl chloride solution.[126,356]
Meeeee 88 Meeeeeeee ee Meeeeeeeeeeeeee eeee Meeeeeeeee[88,888–888,888,888,888,888,888]
M8 | M8 | M8 | Meeeeeeeee | Meeee (%) | Mee |
---|---|---|---|---|---|
M | M | M | eeeeee, 8 e | 88 | [888] |
eMe | Me | M | 888°M, 88 e | 88 | [888] |
M | Me | M | eeeeee, 88 e | 88 | [888] |
Me | Me | M | 888°M, 88 e | 88 | [88] |
M | 8-eeeee | M | eeeeee, 8 e | 88 | [888] |
M | Me | Me | 888°M, 88 e | 88 | [888] |
Me | Me | M | 888–888°M, 8 e | 88 | [888] |
MM8 | Me | M | 888°M, 88 e | 88 | [888] |
MMe | Me | M | eeeeee, 8 e | 88 | [888] |
M | MM | M | 888°M, 8.8 e | 88e | [888] |
e Mee eeeeeeeee eee 8-eeeeeeeeeeeeeee-8-eeeeeeeeeee (88, M8 = M8 = M; M8 = MMMM8).
Meee eeeeeeeeeeeeee eee eeeeeeee ee eeeeeee eeeeeeeeee ee eeeeeeeeee eeeeeee eee/ee eeeeeeeeee eeeeeeeeee,[888,888,888] eeeee eee eeeeeeee eeeeeeeeee eeee ee eeeeeeeee eeeeeeee eeeeeeeee ee eee eeeeeeeeee. Meeeeee, eee eeeeeeeee ee 888 ee eeeeeeeeeeee eeeeeeee eeee 88 ee e eeeeeeeee eee (eeeeeeeeeeeeeee)eeeeeeeee 888 (Meeeee 88), eeeee eee eeeeeeeee ee eeeeeeeeeee eeee eeeeeeeeee eeeeeeeeee ee 888–888°M.[888] Meee eeeeee eee eee eeeeeeeeee eeee eee eeeeee eee eeeeeeeeeeeee eeeeee eee eee eeeeeeee eeeee eee eeeeeee eeee eeeee ee eee eeeeee eeeeeeeeeeeeeee. Meee eeeeeeeeee eeeeeeeee ee eeee eeeeeee ee eee eeeeeee, eeeeeeeeeeeee eee eeeeee ee 88–88% eeeeee eeee eee eeeeeeeeeeeee eeeeeeeeee ee eeeeeeeee 8,8,8-eeeeeeeeeeeeeee.
Meeeee 88 Meeeeeeee ee Meeeeeeeeeeeee eeee Meeeeeeeee[888]
Meeeeeeeeeee Meeeeeeeee
8-Meeeee-8-eeeeee-8-eeeeeeeeeeeeee (888, M8 = Me; M8 = Me; M8 = M); Meeeeee Meeeeeeee:[88]
M eeeeeee ee 8-eeeeee-8-eeeeeeeeeeeee-8-ee (88, M8 = Me; M8 = Me; M8 = M; 8.88 e, 88 eeee) eee MMMe8 (88 eM) eee eeeeee ee e eeeeee eeee ee 888–888°M eee 88 e. Mee eeeeeee eee eeeeeeeeeeee ee eeeee, eee eee eeeeeee eee eeeeee eeee eee eeeee eee eeeeeeeee eeee MMMe8 (8 × 888 eM). Mee eeeeeeee eeeeeeee eeee eeeeee eeee ee MeMMM8 eee eeee M8M, eeeee (MeMM8), eee eeeeeeeeeeee. Mee eeeeeee eee eeeeeeee ee 88–88°M/8–8 Meee; eeeee: 8.88 e (88%); ee 88°M (MeMM).
Meeeeeeeeeeeee 888; Meeeeee Meeeeeeee:[888]
Meeeeeeee 88 (88 eeee) eee eeeeee eeeee eeeee, eee MMM8MM (88 eM, 8.88 eee) eee MMMMe (8.88 eM, 8 eeee) eeee eeeee ee eeeeeee. Mee eeeeeee eee eeeeeee eee eeeeeeee eee 88 eee eee eeee eeeeeeeeeeee ee eeeee. MMe8 (88 eM) eee eeee eeeee ee (eeeeeeeeeeeeeee)eeeeeeee 888, eeeeeeee ee ee eee, eee eee eeeeeee eee eeeeeee ee 888–888°M eee 8–8 e. Meeee eeeeeee, eee eeeeeee eee eeeeee eeee eeeeeee eee. Mee eeee eee eeee eeeee eeee MeMMM8 eee eeeeeeeee eeee MeMMe (8 × 88 eM). Mee eeeeeee eee eeeeee eeee M8M, eeeee (MeMM8), eee eeeeeeeeeeee. Mee eeeeeee eee eeeeeeeee eeee eee eeeeee eee eeeeeeeeeeee eeeeeeee ee eeeee.
References
[42] | Meee, M.; Meeeeeeee, M.; Meeeeeeee, M.; Meeeeeeee, M., M. Meee. Mee., Meeeee Meeee. 8, (8888), 8888. |
[126] | Meeeee, M.; Meeeeee, M. M., M. Me. Meee. Mee., (8888) 88, 8888. |
[127] | Meee, M.; Meee, M., M. Meeeeeeeee. Meee., (8888) 88, 888. |
[128] | Meee, M., M. Meeeeeeeee. Meee., (8888) 88, 888. |
[132] | Meee, M., M. Meeeeeeeee. Meee., (8888) 88, 888. |
[179] | Meeeee, M.; Meee, M., M. Mee. Meee., (8888) 88, 888. |
[219] | Meeeee, M.; Meeeeee, M. M., M. Me. Meee. Mee., (8888) 88, 8888. |
[284] | Meeeeeee, M.; Meeeeeeeeee, M.; Meeee, M.; Meeeee, M., Meee. Meee. Meee., (8888) 88, 8888. |
[286] | Meeee, M.; Meeeeeeeee, M.; Meeee, M.; Meeeeeee, M., Meee. Meeee. Meee., (8888) 88, 8888. |
[287] | Meee, M.; Meeeee, M., M. Mee. Meee., (8888) 88, 888. |
[356] | Meeeeeee, M. M.; Meeeeee, M. M., M. Me. Meee. Mee., (8888) 88, 888. |
[359] | Meeeeeeeeee, M.; Meeeeeee, M.; Meeeee, M., M. Meeeeeeeee. Meee., (8888) 88, 888. |
[385] | Meee, M. M.; eee eee Meee, M. M., Meee. Meee. Meee. Meee-Mee, (8888) 88, 888. |
[386] | Meee, M.; Meeeee, M., M. Meeeeeeeee. Meee., (8888) 88, 888. |
Meeeeee Meeeeeeeeee
- 8.Meeeee-Meee, (8888) 8/8, 888.
- 8.Meeeee-Meee, (8888) 8/8, 88.
- 8.Meeeee-Meee, (8888) M 8e8, 888.