Asymmetric Ugi 3CR on isatin-derived ketimine: synthesis of chiral 3,3-disubstituted 3-aminooxindole derivatives

• Giordano Lesma,
• Fiorella Meneghetti,
• Alessandro Sacchetti,
• Mattia Stucchi and
• Alessandra Silvani

Beilstein J. Org. Chem. 2014, 10, 1383–1389, doi:10.3762/bjoc.10.141

• , Italy Dipartimento di Chimica, Materiali e Ingegneria Chimica ‘Giulio Natta’, Politecnico di Milano, p.zza Leonardo da Vinci 32, 20133 Milano, Italy 10.3762/bjoc.10.141 Abstract An efficient Ugi three-component reaction of a preformed chiral ketimine derived from isatin with various isonitrile and acid

• examples with satisfactory selectivity were achieved to date [32][33][34][35][36]. Results and Discussion Relying on our previous experience, we selected chiral ketimine 1 as a suitable substrate and started to investigate the Ugi three-component reaction (3CR) with tert-butyl isocyanide (2a) and

• upon adding MgBr2, even though this promoter was shown to perform well in other reactions on ketimine 1. Evidently, in this case, the effective protonation of the nitrogen would be required in order to efficiently carry out the attack of the moderately nucleophilic isonitrile. An increase of the

Isocyanide-based multicomponent reactions towards cyclic constrained peptidomimetics

• Gijs Koopmanschap,
• Eelco Ruijter and
• Romano V.A. Orru

Beilstein J. Org. Chem. 2014, 10, 544–598, doi:10.3762/bjoc.10.50

Diastereoselectivity in the Staudinger reaction of pentafluorosulfanylaldimines and ketimines

• Alexander Penger,
• Cortney N. von Hahmann,
• Alexander S. Filatov and
• John T. Welch

Beilstein J. Org. Chem. 2013, 9, 2675–2680, doi:10.3762/bjoc.9.303

• -containing ketimine, with benzyloxyketene in a conrotatory ring closure process. Imine formation and cyclization were possible in spite of the acidification of protons on the carbon bound to SF5. The reactions of the aldimines demonstrated very good 1,2-lk diastereoselectivity, however lack of stereochemical

• control of the C–N ketimine geometry was reflected in the stereochemistry of the product β-lactam. Cyclization of imines with a stereogenic center bearing SF5 was reflected in the 1,2-lk,lk selectivity of the β-lactam. Keywords: aldimine; Cornforth transition state; diastereoselectivity; β-lactam; organo

• pentafluorosulfanylpyruvate 11 (Scheme 3). The ketimine 12, prepared via amine condensation with 11, was reacted as described for the aldimines 5 to form the desired β-lactam 7e. Formation of 7e was accompanied by significantly greater decomposition of 12 and hence 7e was formed in lower overall yields. In contrast to the

Copper-catalyzed aerobic aliphatic C–H oxygenation with hydroperoxides

• Pei Chui Too,
• Ya Lin Tnay and
• Shunsuke Chiba

Beilstein J. Org. Chem. 2013, 9, 1217–1225, doi:10.3762/bjoc.9.138

• . Similarly, it was also revealed that the sp3 C–H oxygenation could proceed directed by the N–H ketimine moieties under Cu-catalyzed aerobic conditions via the corresponding iminyl radical species, where 1,2-diacylbenzenes and amino endoperoxides could be synthesized by C–H oxygenation of secondary and