Fig. 4: Synthesis of fragments F1, F2, F3 and F4. | Nature Synthesis

Fig. 4: Synthesis of fragments F1, F2, F3 and F4.

From: The combination of synthesis and ultra-high-resolution NMR spectroscopy reveals the correct structure of caylobolide A

Fig. 4

a, F1 synthesis. Iterative hydroboration–homologation sequence, followed by boronic ester oxidation and TES protection. F2 synthesis. Diboration of 1, followed by homologation–oxidation, acetonide protection and hydroboration. b, F3 synthesis. Iterative hydroboration–homologation sequence with enantioenriched sulfoxide building blocks to achieve enantiopure fragment 3 in seven steps from 9, installing three stereogenic centres. F4 synthesis. Formation of an enantioenriched stannane followed by a homologation of n-butylboronic acid pinacol ester to afford fragment 4. cod, 1,5-cyclooctadiene; dppe, ethylenebis(diphenylphosphine); Tf, trifluoromethanesulfonyl; DMP, 2,2-dimethoxypropane; dba, dibenzylideneacetone; PPTS, pyridinium p-toluene sulfonate.

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