Conformational control on remote stereochemistry in the intramolecular Pauson–Khand reactions of enynes tethered to homoallyl and homopropargyl alcohols

An intramolecular Pauson–Khand reaction of enynes derived from homoallyl and homopropargyl alcohols is described. 2-Furyl substituted homoallyl and homopropargyl alcohols are easily and efficiently resolved through enzymatic resolution in a high ee (93–99%) with a known stereochemistry. Each enantiomerically enriched enyne affords the conformationally most stable diastereomeric cyclopenta[c]pyran ring system.

Figure optionsDownload as PowerPoint slide

(R)-(+)-1-(Furan-2-yl)but-3-ynyl acetateC10H10O3Ee = 90%[α]D29=+54.6 (c 4.0, MeOH)Source of chirality: enzymatic resolutionAbsolute configuration: (1R)

(S)-(−)-2-(1-(prop-2-ynyloxy)but-3-enyl)furanC11H12O2Ee = 99%[α]D20=-67.5 (c 2.7, CH2Cl2)Source of chirality: enzymatic resolutionAbsolute configuration: (1S)

(S)-(−)-2-(1-allyloxy)but-3-ynyl)furanC11H12O2Ee = 93%[α]D20=-8.5 (c 0.5, MeOH)Source of chirality: enzymatic resolutionAbsolute configuration: (1S)

(3S,4aR)-(+)-3-(Furan-2-yl)-3,4,4a,5-tetrahydrocyclopenta[c]pyran-6(1H)-oneC12H12O3Ee = 99%[α]D20=+35.5 (c 1.7, CH2Cl2)Source of chirality: enzymatic resolutionAbsolute configuration: (3S,4aR)

(3S,7aR)-(+)-3-(Furan-2-yl)-3,4,7,7a-tetrahydrocyclopenta[c]pyran-6(1H)-oneC12H12O3Ee = 93%[α]D20=+99.1 (c 3.6, MeOH)Source of chirality: enzymatic resolutionAbsolute configuration: (3S,7aR)