Orthoamide, XXXIV. Synthesen mit Vinylidendiaminen

Abstract

Orthoamides, XXXIV 1). -Syntheses with VinylidenediaminesVinylidenediamines 2 a, c have been prepared from I-ethoxyvinylamine 4 and dimethylarnine or pyrrolidine, respectively. Heating of 2a and formamidinium acetate affords 4-amino-5-pyrimidinecarbonitrile (7b). Acylation of 2a with acid chlorides or acid anhydrides gives vinylidenediamines 11. The vinylidenediamines 2b and 11 are alkylated by dimethyl sulfate and triethyloxonium tetrafluoroborate, respectively, at the oxygen of the carbonyl group to give the iminium compounds 12 which, on treatment with alkali alkoxides, yield the 1,3-butadienes 13a, b or the vinylogous urea acetals 18a, b. Reaction of morpholine with 13s affords the 1,3-butadiene-1,1,3-triamine 19. CH acidic compounds (malonodinitrile, ethyl cyanoacetate, p-nitrobenzyl cyanide, and nitromethane) react with 13a to give the push-pull substituted 1,3-butadienes 20. In the same way the 1,3-butadiene 23 has been obtained from 22 and malonodinitrile. The pyrimidines 25 and 26 have been prepared from 13a and 18a and amidines or guanidines, respectively. Reaction of 18a with phenylhydrazine gives a mixture of the isomeric pyrazoles 29 and 30. Hydroxylamine reacts with 18a to yield the 1 ,2-oxazole 31. Reaction of isocyanates and phenyl isothiocyanate with 13a affords the acylated 1,3-butadienes 32. On heating 32a undergo cyclization to furnish the a-pyridone 33, while thermolysis of 32e affords the y-pyridone 37. On treatment with methyl isothiocyanate 13a and b undergo cyclization to yield the a-pyridinethiones 38.

Synthesis and properties of β,β-bisfunctionalised keteneN,N-acetals

“…18 Finally, the synthesis of various pyridones based on alkoxydienediamine vinylogues 146 and 147 should be noted. 70 Thermolysis of N-acylaminals 148 results in substituted oxazin-6-ones 149. 29 Another method for the synthesis of substituted 1,3-oxazin-6ones has also been reported.…”

“…20 Alkoxydienediamines are also convenient starting compounds for pyrimidine synthesis. 70 For example, diamine 116 reacts with amidines to give substituted pyrimidines 164. Compound 165 is also formed upon treatment of diamidine 131 with DMF diethyl acetal.…”

“…68,69 Orthoamidoesters 52 also enter into similar reactions to give aminals 53. 70,71 It should be noted that compounds 52 are much more reactive than urea acetals 51.…”

“…Compound 116 is a convenient starting reagent for the synthesis of various dienamines, e.g., dienediamine 117 or dienetriamine 118. 70 Yet another reaction of ketene aminals with electrophilic reagents worthy of note is that of enediamino diketones with the Lawesson reagent (LR). For example, enediamino diketone 119 can be converted to the corresponding enediamino dithione 120.…”

Synthesis and Chemistry of α,β‐Didehydroamino Acids

“…The nitro group of the unsaturated esters can be reduced easily without affecting the double bond using aluminum amalgam [68], zinc in glacial acetic acid [69], or by catalytic hydrogenation using Raney nickel [70] or Pt/C [71]. According to comparable reactions described for the nitro acetates, orthoformates [76] and dimethylformamide acetals [77] give rise to the corresponding b-alkoxy or b-amino substituted DDAAs. Condensation with aldehydes [72] and ketones [73] in aprotic solvents gives rise to N-formylated DDAAs, probably via oxazoline intermediates [74].…”