No abstract

A diastereo- and enantioselective aldol reaction between aldehydes and a synthetically useful ketomalonate 1c as a hydrated form was developed, and either anti- or syn-aldol adducts having a chiral tetrasubstituted carbon center were obtained in high enantioselectivities by use of a tetrazole analogue of L-proline (S)-2 or an axially chiral amino sulfonamide (S)-3 as catalyst.

Catalytic asymmetric syntheses of various isoxazoline-N-oxides have been accomplished by asymmetric phase-transfer conjugate addition of bromomalonate to nitroolefins and subsequent ring-closing O-alkylation.

Catalytic asymmetric synthesis of various isoxazoline-N-oxides having a tetrasubstituted carbon has been accomplished by asymmetric phase-transfer conjugate addition of bromomalonate to nitroolefins and subsequent ring-closing O-alkylation. The obtained isoxazoline-N-oxide was readily converted to the corresponding oxime, isoxazoline, and lactam without loss of optical purity.

Je nach Katalysator – L‐Prolin oder ein axial‐chirales Aminosulfonamid – liefert die hoch diastereo‐ und enantioselektive Mannich‐Reaktion eines Ketimins mit Aldehyden fast stereoisomerenrein syn‐ oder anti‐Mannich‐Produkte mit tetrasubstituierten Stereozentren (siehe Schema; Tf=Trifluormethansulfonyl).