Version 2 2021-11-29, 14:07Version 2 2021-11-29, 14:07
Version 1 2021-11-23, 20:07Version 1 2021-11-23, 20:07
journal contribution
posted on 2021-11-29, 14:07authored byBaiyang Jiang, Mingji Dai
We report the convergent total synthesis
of (±)-hamigeran
M, enabled by five C–H functionalization reactions and proceeding
in 11 steps in 3.9% overall yield. The C–H functionalizations
include a hydroxy-directed C–H borylation, one C–H metalation-1,2-addition,
one C–H metalation-Negishi coupling, a late-stage oxazole-directed
C–H borylation-oxidation, and one electrophilic bromination.
Two of these five C–H functionalizations forged strategic C–C
bonds in the seven-membered ring of hamigeran M. The oxazole-directed
C–H borylation-oxidation was unprecedented and ensured a late-stage
hydroxylation. Other key steps include a tandem Suzuki reaction-lactonization
to join the cyclopentane building block with the aromatic moiety and
a hydrogen-atom transfer reaction to reduce a challenging tetrasubstituted
double bond.