Smith, Dong, Brenneman, Fox. JACS, 2009, ASAP. DOI: 10.1021/ja9052366.
Read the first post?  Good.  Let’s get on with the one remaining fragment, a further DHP.  Work on this fragment was conducted via a coupling of an enone with the ready-elaborated sidechain – reaction that might be a little sluggish, as the enol functionality is again working against the group.  However, forming a cuperate of the vinyl bromide solved this, allowing a highly selective and reasonably high yielding reaction (60%, 20:1 d.r.).  BTW, the two fragments weren’t particularly …

Smith, Dong, Brenneman, Fox. JACS, 2009, ASAP. DOI: 10.1021/ja9052366.
I thought I’d re-start after holiday with a tasty target, and sorangicin A certainly fits the bill.  It’s not often that I have to draw such an exotic structural motif into a target (though in reality it’s not far removed from a DHP); always a welcome feature in a synthesis.  But sorangicin A is more than just a structural challenge – it’s quite an antibiotic, with broad-spectrum activity against both Gram-positive and Gram-negative strains.  With the funding proposal …

Micalizio and Macklin. JACS, 2009, ASAP. DOI: 10.1021/ja809491b.
An interesting test-case for new methodology, this family of diterpenes has a pretty novel architecture. The unsaturated sidechain is the bit I find intreguing, as skipped-conjugation is tricky to keep that way. Oh, there’s some bio-stuff to provide a little rationale (including a bit of bacteria growth inhibition, and some cytotoxicty), but nothing startling. Micalizio is in it for the chemistry, and concern about the C-11 stereocenter, which was unassigned when they started their work…

As they didn’t …