| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 5275921 | Tetrahedron Letters | 2007 | 4 Pages |
The syntheses and 13C NMR analyses of four diastereomeric butenolides, two of which were recently isolated from the marine microorganisms Streptomycete B 5632 and Streptoverticillium luteoverticillatum 11014 are described. The two isolated butenolides were found to be one of the two diastereomers (4S,10Râ,11Râ)-4,11-dihydroxy-10-methyl-dodec-2-en-1,4-olide (RRS-1 or SSS-1) and one of the two diastereomers (4S,10Sâ,11Râ)-4,11-dihydroxy-10-methyl-dodec-2-en-1,4-olide (SRS-1 or RSS-1). An asymmetric 1,3-dipolar cycloaddition of a thiocarbonyl ylide with a dipolarophile attached to camphorsultam and a ring-opening of an enantiomerically pure vinyloxirane by lithiated dithiane served as key steps for the construction of the three stereogenic centres. Further elaborations including ring-closing metathesis and Mitsunobu inversion furnished the four diastereomeric butenolides.
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