Asymmetric multicomponent reactions: convenient access to acyclic stereocenters and functionalized cyclopentenoids

Asymmetric multicomponent reactions of optically active phenyl dihydrofuran, keto ester or N-tosyl imino ester, and allylsilane provided functionalized phenyl tetrahydrofurans with multiple stereogenic centers diastereoselectively. Cleavage of the resulting substituted tetrahydrofurans readily provided acyclic derivatives with three contiguous asymmetric centers via an acyloxycarbenium ion intermediate. Ring closing olefin metathesis, using Grubbs catalyst, afforded functionalized cyclopentene derivatives in optically active form. A one-pot tandem tetrahydrofuran ring cleavage followed by ring closing olefin metathesis also provided functionalized cyclopentenes in good yield.

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(R)-2-Phenyl-2,3-dihydrofuranC10H10O4[α]D23=-66(c1.05,CHCl3)Absolute configuration: (R)

(R)-Ethyl2-((2R,3R,5R)-2-allyl-5-phenyltetrahydrofuran-3-yl)-2-hydroxypropanoateC18H24O4[α]D23=+15.7(c1.3,CHCl3)Absolute configuration: (2R,3R,5R)

(S)-Ethyl2-((2R,3S,5R)-2-allyl-5-phenyltetrahydrofuran-3-yl)-2-hydroxy-4-methoxybutanoateC20H28O5[α]D25=-15.3(c1.2,CHCl3)Absolute configuration: (S,2R,3S,5R)

(3R,4S,5R)-3-(Ethoxycarbonyl)-1-methoxy-4-styryloct-7-ene-3,5-diyl diacetateC10H10O[α]D23=+44.9(c1.0,CHCl3)Absolute configuration: (3R,4S,5R)

(R)-Ethyl 2-acetoxy-2-((1S,5R)-5-acetoxycyclopent-2-enyl)propanoateC14H20O6[α]D23=-3.5(c1.0,CHCl3)Absolute configuration: (R,1S,5R)

(R)-Ethyl 2-acetoxy-2-((1S,5R)-5-acetoxycyclopent-2-enyl)-4-methoxybutanoateC16H24O7[α]D23=-3.2(c1.0,CHCl3)Absolute configuration: (R,1S,5R)

(S)-Ethyl 2-acetoxy-2-((1S,5R)-5-acetoxycyclopent-2-enyl)-4-methoxybutanoateC10H10O[α]D23=-5.5(c1.0,CHCl3)Absolute configuration: (S,1S,5R)

(R)-Ethyl 2-((2R,3R,5R)-2-allyl-5-phenyltetrahydrofuran-3-yl)-2-(4-methylphenylsulfonamido)acetateC24H29NO5S[α]D23=-11.8(c0.9,CHCl3)Absolute configuration: (R,2R,3R,5R)

(S)-4-((2R,3R,5R)-2-Allyl-5-phenyltetrahydrofuran-3-yl)-3-tosyloxazolidin-2-oneC23H25NO5S[α]D23=-32.5(c1.6,CHCl3)Absolute configuration: (S,2R,3R,5R)

(3R,4R)-3-(2-Oxo-3-tosyloxazolidin-4-yl)-1-phenylhepta-1,6-diene-4-yl acetateC25H27NO6S[α]D23=+41.4(c1.05,CHCl3)Absolute configuration: (3R,4R)

(1R,2R)-2-((R)-2-Oxo-3-tosyloxazolidin-4-yl)cyclopent-3-enyl acetateC17H19NO6S[α]D23=-87.4(c0.85,CHCl3)Absolute configuration: (1R,2R,R)