Total Synthesis of Stachybotrys microspora Triprenol Phenol-7 (SMTP-7).

The first total synthesis of triprenol phenol (SMTP)-7 is described. Establishment of the two pyran ring stereogenic centers and key reactions featuring a double reductive amination and a double lactam ring formation in flow are described. The (2,3)--benzopyran intermediate , isolated by chiral preparative SFC chromatography, was carried forward to afford SMTP-7.

The Chelate Effect Rationalizes Observed Rate Acceleration and Enantioselectivity in BINOL-Catalyzed Petasis Reactions.

Density functional theory (DFT) calculations afforded insight into the origin of the experimentally observed reaction rate acceleration (≥500 fold) and enantioselectivity (≥99 % ee) of 1,1'-bi-2-naphthol- (BINOL-) catalyzed three-component Petasis reactions . BINOL accelerates the rate determining step by forming a B chelate, which involves the loss of water from the hemiaminal moiety to generate an iminium intermediate. Subsequent vinyl group transfer from B to the iminium carbon affords the enantiomerically enriched product and a cyclic trigonal B(III)BINOL complex, which rapidly releases the BINOL allowing it to re-enter the catalytic cycle.