Diethylboron triflate-promoted anti aldol additions of Oppolzer’s sultam

An excess of diethylboron triflate leads to high anti diastereoselectivity (up to 98:2) in aldol additions employing Oppolzer’s sultam with both aliphatic and aromatic aldehydes.

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(2R)-N-[(2S,3S)-3-Hydroxy-2-methylhexan-1-oyl] bornane-10,2-sultamC17H29NO4SEe 100%[α]D = −23.5 (c 1.0, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (2S,3S)

(2R)-N-[(2S,3S)-3-Hydroxy-2-methylpentan-1-oyl] bornane-10,2-sultamC16H27NO4SEe 100%[α]D = −65.6 (c 0.99, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (2S,3S)

(2R)-N-[(2S,3S)-3-Hydroxy-2-methylbutan-1-oyl] bornane-10,2-sultamC15H25NO4SEe 100%[α]D = −58.1 (c 0.85, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (2S,3S)

(2R)-N-[(2S,3S)-2,4-Dimethyl-3-hydroxypentan-1-oyl] bornane-10,2-sultamC17H29NO4SEe 100%[α]D = −71.7 (c 2.24, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (2S,3S)

(2R)-N-[(2S,3S)-3-Hydroxy-2-methyl-3-phenylpropan-1-oyl] bornane-10,2-sultamC20H27NO4SEe 100%[α]D = +7.1 (c 1.1, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (2S,3R)

(2S)-N-[(2S,3R)-3-Hydroxy-5-(trimethylsilyl)pent-4-yne-1-oyl] bornane-10,2-sultamC19H31NO4SSiEe 100%[α]D = −56.4 (c 1.1, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (2S,3R)