Asymmetric Lewis acid catalyzed addition of isocyanides to aldehydes. Synthesis of 5-amino-2-(1-hydroxyalkyl)oxazoles
Stannous chloride efficiently catalyzes condensations between alpha -isocyanoacetamides C==NCHRCOR1 (I, R = H, PhCH2; R1 = N-morpholinyl, Et2N) and a variety of aldehydes to afford the corresponding 5-amino-2-(1-hydroxyalkyl)oxazoles II (R2 = Et, n-C6H13, Me2CH, cyclohexyl, tert-Bu, COOEt, Ph, etc.) in good to excellent yields. The Sn-(R)-Ph-PyBox2-catalyzed reaction between I (R = PhCH2; R1 = N-morpholinyl) and 2-(benzyloxy)acetaldehyde shows an isoinversion effect, with the max. enantiomeric excess of oxazole II (R2 = PhCH2OCH2) (80%) obtained at -40 Deg. [on SciFinder (R)]
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Wang, S., Wang, M.-X., Wang, D.-X., & Zhu, J. (2007). Asymmetric Lewis acid catalyzed addition of isocyanides to aldehydes. Synthesis of 5-amino-2-(1-hydroxyalkyl)oxazoles. European Journal of Organic Chemistry, (24), 4076–4080. https://doi.org/10.1002/ejoc.200700340
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