Synthesis of the C20-C32 Tetrahydropyran Core of the Phorboxazoles and the C22 Epimer via a Stereodivergent Michael Reaction

TY - JOUR

T1 - Synthesis of the C20-C32 Tetrahydropyran Core of the Phorboxazoles and the C22 Epimer via a Stereodivergent Michael Reaction

AU - Clarke, Paul Andrew

AU - Ermanis, Kristaps

PY - 2012/11/2

Y1 - 2012/11/2

N2 - A stereoselective synthesis of the C20-C32 tetrahydropyran core of the phorboxazoles has been achieved in only seven steps and in a 31% overall yield. The C22 epimer was also synthesized. The key step was a silyl ether deprotection/oxy-Michael cyclization. When this step was conducted under Bronsted acid conditions, the C20-C32 core was formed with the desired 2,6-cis-stereochem. However, when the silyl ether deprotection/oxy-Michael cyclization was conducted under fluoride conditions buffered with acetic acid, the C22 epimer of the core was the sole product.

AB - A stereoselective synthesis of the C20-C32 tetrahydropyran core of the phorboxazoles has been achieved in only seven steps and in a 31% overall yield. The C22 epimer was also synthesized. The key step was a silyl ether deprotection/oxy-Michael cyclization. When this step was conducted under Bronsted acid conditions, the C20-C32 core was formed with the desired 2,6-cis-stereochem. However, when the silyl ether deprotection/oxy-Michael cyclization was conducted under fluoride conditions buffered with acetic acid, the C22 epimer of the core was the sole product.

UR - http://www.scopus.com/inward/record.url?scp=84868348772&partnerID=8YFLogxK

U2 - 10.1021/ol3026523

DO - 10.1021/ol3026523

M3 - Article

SN - 1523-7060

VL - 14

SP - 5550

EP - 5553

JO - Organic Letters

JF - Organic Letters

IS - 21

ER -