Reaction of isoquinolines 1 with N-arylsulfonylamino acid fluorides 2 provides a highly stereoselective access to new dihydroimidazo[2,1-a]isoquinolin-3-ones 5 via intermediate N-acylisoquinolinium salts 3. Addition reactions to the enamine double bond, such as hydrogenation or epoxidation with dimethyldioxirane, leads to tetrahydroimidazo[2,1-a]isoquinoline-3-ones 6, 7 and oxiranes 8, respectively. Opening of the oxirane ring of the 8 with nucleophiles allows the synthesis of hydroxytetrahydroimidazo[2,1-a]isoquinolin-3-ones

Asymmetric synthesis of Reissert compounds 5, 12 was achieved using chiral acyl halides such as amino acid fluorides or (-)-(R)-menthylchloroformate and TMSCN. These are the first cases of asymmetric synthesis of unsubstituted isoquinoline-derived Reissert compounds with high stereoselectivities. The chiral Reissert compound 12 could be alkylated in position 1 affording 1-substituted Reissert compound 13 highly stereoselectively. The products are potential starting materials for unnatural amino acids and alkaloid analogues.

Fused pyridine derivatives R 0450Asymmetric Synthesis of Isoquinoline Derivatives from Amino Acids. -Reaction of isoquinolines (I) and (XIV) (cf. following scheme) with N-arylsulfonylamino acid fluorides (II) provides a straightforward and highly stereoselective access towards dihydroimidazoisoquinolines. A variety of reactions at the enamine moiety is studied. They involve the double bond hydrogenation, dimerization and highly stereoselective epoxidation reaction. Regiospecific and highly stereoselective oxirane ring opening of the epoxide (VIII) is achieved with diverse nucleophiles like amines, methanol or Tms-O-Tf (to be continued). -(SIECK, O.; EHWALD, M.; LIEBSCHER*, J.; Eur.

Fused pyridine derivatives R 0450 Asymmetric Synthesis of Isoquinoline Derivatives from Amino Acids. -When dihydroisoquinoline (XX) reacts with O-silylmandelic acid chloride (XXI), the tetrahydrooxazoloisoquinoline (XXII) is formed similarly to the dihydroimidazoquinolines. -(SIECK, O.; EHWALD, M.; LIEBSCHER*, J.; Eur.