[Development of solid-phase radical reactions using oxime ethers as a radical acceptor].
Triethylborane has the potential to induce radical reactions on solid support and the solid-phase radical reactions were achieved by using triethylborane as a radical initiator. The intermolecular carbon radical addition to glyoxylic oxime ether anchored to Wang resin proceeded under very mild conditions to give alpha-amino acid derivatives in good yield without interference of the polystyrene skeleton of the resin. Diethylzinc also worked well as a radical initiator at low reaction temperature. Thus, the employment of triethylborane or diethylzinc at low reaction temperature facilitated the control of stereochemistry in solid-phase reactions. Alkyl radical addition to Oppolzer's camphorsultam derivatives of oxime ether anchored to a polymer support proceeded smoothly even at -78 degrees C to give the alpha-amino acid derivatives with excellent diastereoselectivities. The radical cyclization of oxime the ethers anchored to a polymer support also proceeded effectively to provide functionalized pyrrolidines via a carbon-carbon bond-forming process.
Miyabe
H
H
Kobe Pharmaceutical University, Japan.
D000596:Amino Acids; D001880:Boranes; D002244:Carbon; D002625:Chemistry, Organic; D003500:Cyclization; D004987:Ethers; D006038:Glyoxylates; D055601:Organic Chemistry Phenomena; D010091:Oximes; D011108:Polymers; D011759:Pyrrolidines; D012116:Resins, Plant; D013696:Temperature
D000596:Amino Acids; D001880:Boranes; D004987:Ethers; D006038:Glyoxylates; D010091:Oximes; D011108:Polymers; D011759:Pyrrolidines; D012116:Resins, Plant; D002244:Carbon; C079756:triethylborane