Anti-selective glycolate aldol additions with an oxapyrone boron enolate.
The boron enolate of pyrone 2 undergoes asymmetric aldol reactions with aldehydes to give protected anti 1,2-diols 3. The pyrone is readily available from trans stilbene using asymmetric dihydroxylation. Yields for the aldol reaction range from 62 to 92% and the selectivities from 6:1 to >20:1 for the anti isomers. Protection and hydrogenolysis of the products can be used to remove the pyrone, giving differentially protected diol intermediates 12 that are amenable to multistep synthesis.
Andrus
M B
MB
Department of Chemistry and Biochemistry, C100 BNSN, Brigham Young University, Provo, Utah 84602, USA. mbandrus@chemdept.byu.edu
Sekhar
B B
BB
Meredith
E L
EL
Dalley
N K
NK
D000447:Aldehydes / Q000737:chemistry; D001896:Boron Compounds / Q000737:chemistry*; D006016:Glycolates / Q000737:chemistry*; D006018:Glycols / Q000138:chemical synthesis / Q000737:chemistry; D011753:Pyrones / Q000737:chemistry*; D013237:Stereoisomerism
D000447:Aldehydes; D001896:Boron Compounds; D006016:Glycolates; D006018:Glycols; D011753:Pyrones