Potassium reaction with, phosgene

Reactions.—Mono-A -alkylation of simple amides can be achieved by treatment of the corresponding amide methylols with trialkylaluminium reagents. Dipole-stabilized carbanions (166) can be formed from AW-dimethylbenzamides by treatment with s-butyl-lithium these react normally with a range of electrophiles leading to analogues of the N-methyl group. ° The little-studied A -ynamides (167) are accessible from secondary amides by sequential reaction with phosgene, a nucleophile, and potassium t-butoxide. ... 

Ompoimd (13) has been prepared ftom 2-chloro-3-nitropyridine by a four-step sequence (treatment with NaHS, reduction with tin(Q)chloride, diazotization with nitrous acid and treatment with carbon disulfide at 220°Q[72],[85]. Compound (14) has been prepared by treatment of disodium 5-cyanoisotiilaz-oledithiolate with thiophosgene [83], [86]. Con unds (15)-(17) have beai prepared by a two-step sequence (treatment with KHS or NaHSe and reaction with thiophosgene) [78],[82]. Reactions with phosgene yielded the corresponding -2-ones [78],[82],[83],[86]. Compounds (15),(17) have been prepared also by treatment of 2,3-dichloropyrazine and 2,3-dichloro-5,6-dimethylpyrazine respe vely, with potassium tiithiocarbonate [78]. 

Azide 367 is prepared from 4-r -butyl-2-nitroaniline in 76% yield by its diazotization followed by treatment with sodium azide. In a 1,3-dipolar cycloaddition with cyanoacetamide, azide 367 is converted to triazole 368 that without separation is directly subjected to Dimroth rearrangement to give derivative 369 in 46% yield. Reduction of the nitro group provides ortfc-phenylenediamine 371 in 91% yield <2000EJM715>. Cyclocondensation of diamine 371 with phosgene furnishes benzimidazol-2-one 370 in 39% yield, whereas its reaction with sodium nitrite in 18% HC1 leads to benzotriazole derivative 372, which is isolated in 66% yield (Scheme 59). Products 370 and 372 exhibit potassium channel activating ability <2001FA841>. 

Conversion of 2 to the highly crystalline oxazolidinone 3 with phosgene has been described by Thornton who has employed this substance as a chiral auxiliary in asymmetric aldol reactions of its N-propionyl derivative. Kelly has also used an oxazoline derived from 3 as a chiral auxiliary in asymmetric alkylation of a glycolate enolate. Oxazolidinone 3 has also been prepared from 2 with diethyl carbonate in the presence of potassium carbonate. The conversion of 2 to the oxazolidinone 3 is accomplished using triphosgene in this procedure because of the high toxicity of phosgene. 

Phosgene reacts, sometimes violently, with a large number of common inorganic (Chapter 9) and organic (Chapter 10) substances. Hazardous reactions with lithium, sodium, potassium, aluminium, lithium amide, hexa-2,4-diyn-l, 6-diol, propan-2-ol, and hexafluoropropene have been mentioned specifically [1787]. Mixtures of potassium and phosgene are reported to explode when subjected to shock [1913a]. In addition, phosgene... 

Reaction of the potassium salt of 3-aminobenzo[h]thiophene-2-carboxylic acid with phosgene gave the corresponding anhydride [412] ... 

The reaction of phosgene with a two molar equivalent of a potassium... 

Sulfur tetrafluoride is a hazardous and highly toxic gas [4], in some aspects comparable with phosgene [12]. For reactions with SF4 with or without HF autoclaves made from Hastelloy C with Monel 400 piping and valves are recommended [13]. When handling SF4 sufficient ventilation must be provided and protective goggles and gloves should be worn. On autoclave depressurization, excess SF4 and HF should be scrubbed with potassium hydroxide solution. 

Perimidinones are available from 1,8-naphthalenediamines in cyclization reactions with potassium cyanate, carbonate, and chlorocarbonate esters, phosgene, and urea all methods give satisfactory results. 2-Alkoxy- and aryloxyperimidines are readily available by nucleophilic substitution reactions in the 2-position <81RCR8I6>. 

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