ISSN:
0009-2940
Schlagwort(e):
Aziridines, 2-imino-, chiral, non-racemic
;
Imidoyl halides, 2-halo
;
Imidates, 2-chloro
;
1,3,2-Thiazaphos-pholidines
;
Amidines, 2-halo
;
1,3-Elimination, inversion of configuration in
;
E/Z Diastereomerization
;
[2 + 1] Cycloreversion, kinetics of thermal
;
Chemistry
;
Inorganic Chemistry
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
Notizen:
The 2-halo imidoyl chlorides 7 are obtained from the amide 5 and the 2-halo amides 6 by the action of phosphorus pentachloride and thionyl chloride, respectively. Non-racemic (S)-6a is converted into 7a which is racemic, however. The reaction of Lawesson's reagent with 6a furnishes the diaste-reomeric 1,3,2-thiazaphospholidine derivatives 15. Treatment of (S)-6a (98% ee) with methyl triflate affords 2-chloro imidate 8 (95% ee) which reacts with methanamine in the presence of methanammonium chloride to yield the 2-chloro amidine (S)-9a (90% ee). The 2-halo imidoyl halides 7a and b react with methanamine to produce the 2-halo amidines 9a and b. - Strong bases, e.g. potassium tert-butoxide or sodium hydride in the presence of catalytic amounts of tert-butyl alcohol, eliminate hydrogen chloride or bromide from the 2-halo amidines 9a and b and (S)-9ato yield mixtures of the 2-iminoaziridines (E)- and (Z)-4, and (E,R)- and (Z,R)-4 (83% ee), respectively. The 1,3-elimination of hydrogen bromide from 9b is diastereoselective at -30 to -40° [(E)-4:(Z)-4 = 〈10:〉90]. The diastereomers equilibrate at 36° with (kEZ + kZE) = (5.92 ± 0.08) . 10-5 s-1 (K = kEZ/kZE = 0.428 ± 0.013). - The thermolysis of (E)- and (Z)-4 in [D6]benzene solution yields the imine 16 and methyl isocyanide (17). The decomposition follows the first-order rate law. The following Arrhenius and Eyring parameters are calculated from five rate constants obtained in the temperature range of 70-110°: Ea = (115.2 ± 0.4) kJmol-1, IgA = (12.06 ± 0.28), δH
Zusätzliches Material:
2 Ill.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/cber.19941270921
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