Scheme 4. Semi-synthesis of alkyne-linked C16-aminoratjadones. Reagents and conditions: (a) NH₄OAc (2.0 equiv.), NaBH₃CN (2.0 equiv.), (MeOH), 23 °C, 4h, 68% of 33 as 2 : 1-mixture of diastereomers; (b) 24 (1.1 equiv.), NMM (6.0 equiv.), (CH₂Cl₂), 23 °C, 20 h, 62% of 34 as a 2 : 1 mixture of diastereomers; (c) propargylamine (2.0 equiv.), NaBH₃CN (2.0 equiv.), (MeOH), 23 °C, 4 h, 99% of 35 as a 2 : 1-mixture of diastereomers.