Fig. 6: Further functionalizations of nitroso acetal products 4d and 4t. | Nature Catalysis

Fig. 6: Further functionalizations of nitroso acetal products 4d and 4t.

From: Harnessing the ambiphilicity of silyl nitronates in a catalytic asymmetric approach to aliphatic β3-amino acids

Fig. 6: Further functionalizations of nitroso acetal products 4d and 4t.

a, Reduction of compounds 4d and 4t to the corresponding N-Boc β-amino acid esters 5d and 5t. b, Practical multi-gram three-step sequence from 1-nitrohexane to β-amino acid ester 5t followed by downstream modifications: (1) NaBH4, MeOH, THF, 65 °C, 20 h, (2) (step i) TFA, CH2Cl2, 25 °C, 20 min, (step ii) LDA, THF, –78 °C, 3 h; (3) NaOH, MeOH, 0 → 25 °C, 2 h; (4) Phe-OMe⋅HCl, HATU, (i-Pr)2NEt, CH2Cl2, 25 °C, 16 h; (5) (step i) TFA, CH2Cl2, 25 °C, 20 min, (step ii) Boc-Pro-OH, HATU (hexafluorophosphate azabenzotriazole tetramethyl uronium), NEt3, CH2Cl2, 25 °C, 16 h.

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