Stereoselective first total synthesis of (R)-rugulactone

A simple and highly efficient stereoselective synthetic route has been developed for the synthesis of (R)-rugulactone, a 6-arylalkyl-5,6-dihydro-2H-pyran-2-one, from readily available substrates such as 1,3-propanediol and 3-phenyl-1-propanal employing Keck’s asymmetric allylation and cross metathesis as key steps.

Figure optionsDownload as PowerPoint slide

(R)-6-(Benzyloxy)-1-hexen-4-olC13H18O2[α]D25=+2.2 (c 1, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (4R)

[1-(2-Benzyloxy-ethyl)-but-3-enyloxy]-tert-butyl-diphenyl-silaneC29H36O2Si[α]D25=-6.3 (c 1, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (3R)

3-(tert-Butyl-diphenyl-silanyloxy)-hex-5-en-1-olC22H30O2Si[α]D25=-23 (c 1, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (3R)

(5R)-5-(tert-Butyl-diphenyl-silanyloxy)-octa-2, 7-dienoic acid methyl esterC25H22O3Si[α]D25=+13.6 (c 1, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (2Z,5R)

(6R)-6-Allyl-5, 6-dihydro-pyran-2-oneC8H10O2[α]D25=-115.8 (c 1, CHCl3).Source of chirality: asymmetric synthesisAbsolute configuration: (6R)

6-(4-Oxo-6-phenyl-hex-2-enyl)-5,6-dihydro-pyran-2-oneC17H18O3[α]D25=-61.9 (c 0.5, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (6R,8Z)