Biosynthesis of tetronasin: Part 7. Preparation of structural analogues of the tetraketide biosynthetic precursor to tetronasin
作者:Simon L. Less、Peter F. Leadlay、Christopher J. Dutton、James Staunton
DOI:10.1016/0040-4039(96)00601-6
日期:1996.5
The preparation of three structuralanalogues of the putative tetraketide biosyntheticprecursor (2) of the acyl tetronic acid ionophore tetronasin, as N-acetylcysteamine thioesters (3), (4) and (5) is described. Two examples are 19F-labelled.
The 16-membered macrodiolide elaiolide (2) has been prepared in 20 steps from the ketone (S)-8 in 9.3% overall yield with a diastereoselectivity of 76%, Key steps included the copper(I) thiophene-2-carboxylate promoted cyclodimerization of the vinyl stannane 3 to give the C-2-symmetric macrocycle 16 in 80% yield and the two directional aldol coupling of the macrocyclic diketone 17 with aldehyde 5. Most of the stereocenters in the macrocyclic precursor 3 were constructed using boron aldol methodology developed in this laboratory.