Thermolyse von Oxazolin‐5‐onen, XI¹⁾N‐Acylimine und Enamide durch Gasphasenpyrolyse von 4‐Alkyl‐2‐oxazolin‐5‐onen

Abstract

4-Alkyl-2-oxazolin-S-one 1 liefern bei der Gasphasenpyrolyse unter CO-Verlust N-Acylimine 2, die sich beim Vorhandensein a-stilndiger H-Atome in die stabileren Enamide 3 umlagern. 1st diese Umlagerung durch ein quartilres C-Atom verhindert, so lassen sich die N-Acylimine (z. B. 29) isolieren. Im Falle des 4,4-dialkylsubstituierten Oxazolinons 1 o entstehen Gemische von N-Acylimin 20 und Enamid 30, wobei der Anteil des letzteren bei ErhOhung der Pyrolysetemperatur zunimmt. Thermolysis of Oxazolin-5-ones, XI t j N-Acyllmina and Enamides via Cis Phase Pyrolysis of ~AIkyl-2-oxazolin-5-on~On gas phase thermolysis 4-alkyl-2-oxazolin-5-ones 1 undergo CO elimination to yield N-acylimines 2. which rearrange into more stable enamides 3 if a-hydrogens are present. N-Acylimines (e. g. 2r) may be isolated in cases where the rearrangement is prevented by a quarternary C-atom. The 4,4-dialkylsubstituted oxazolinone 1 o yields mixtures of N-acylimine 2 0 and enamide 3 0 , the amouni of the latter increasing at higher pyrolysis temperatures. Die Konstitution dieser Verbindung wird durch eine breite 1R-Bande (CHC1,) im Carbonylbereich bei 1705-1650 cm-' und das Singulett des Imino-Protons im 'H-NMR-Spektrum (CDCI,) bei S = 7.94 bewiesen'). Beim Erhitzen

Nucleophilic Addition to Imines and Imine Derivatives

“…64a The intermediacy of a titanium amide tetraisopropoxide ate complex (79) which can condense with aldehydes to form the reactive titanium complex (80), has been proposed (Scheme 14). In addition, amine N-oxides (82) can be treated with trialkylsilyl triflates to generate, after methyllithium treatment, a-siloxyamines (83) which, when allowed to react with Grignard reagents (or trialkylaluminum), generate tertiary amines (84) in modest yields (Scheme 15).65 (82) ii, MeLirrHF o RM 0 lR (84) O'Donnell et al 66 have examined benzophenone-derived glycine acetate (85) as a glycine cation equivalent. Higher order mixed cuprates [R2Cu(CN)Li2J react with (85) to afford alkylated Schiff base (86) in moderate yields.…”

“…Almost all substituted N-halomethylamides lack~-hydrogen atoms due to the propensity of N-acylimines to tautomerize to acyl enamides. 83 Complex alkenyl-copper and -cuprate derivatives, and also alanates, have been generated with high stereochemical purity, and upon treatment with N-chloromethyl-N-methylfonnamide or N-chloromethylphthalimide provide access to highly functionalized allylic amides (entries 1 and 2, Table 7). 84 Addition to acyliminomalonic esters 85 or acyliminophosphonates 86 provides acylaminomalonates and acylaminoalkylphosphonates in modest yield (entries 3 and 4, Table 7).…”

Thermolysis of polyazapentadienes. Part 11. Concerted and free radical mechanisms in 2-aza enone and 2-aza enthione pyrolyses: crystal and molecular structures of 3-dimethylamino-1-p-tolyl-2-azaprop-2-en-1-one and 3-dimethylamino-1-phenyl-2-azaprop-2-ene-1-thione

“…1 660 ,cm-' (CO); 6,7.7-6.9 (1 5 H, m); 6, 178.98 (q), 167.47 (q), and overlapping and 2.34 (3 H, s); 6,179.06 (q), 167.29 (q), 143.31 (q), 136.39 (q), overlapping benzenoid signals in the range 128-131, and 21.39; m/z 299 ( M + , 43%), 119 (loo), 91 (47), 77 (24), and 51 (11). These compounds were particularly prone to hydrolysis, and were normally stored at -20 "C.…”

The Synthesis of Ketone‐Derived Enamides by Elimination of HCN from Cyanoamides

“…be prepared. [18] Several methods for the preparation of unstabilised ketonederived enamides (shown in Scheme 2 with acetone-derived enamides as examples) have been reported but are inconvenient for the following reasons: i) palladium-catalyzed rearrangement of acyl aziridine 4 starts from carcinogenic aziridines; [19] ii) the pyrolysis of dimethylazlactone 5 is high yielding but requires the use of special equipment, and provides the product mixed with its tautomeric acyl imine; [20] and iii) gas phase ther-Scheme 2. The Z geometry of the product enamide is highly favoured, and the regioselectivity can be directed by one′s choice of protecting group.…”