Studies towards the total synthesis of (-)-α-Kainic acid

• Main Author: Lai, Jason
• Published: University of Sussex 2012
• Subjects: 547.59; QD0241 Organic chemistry
• Online Access: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.556441

For images please see Abstract in pdf trans-4-Hydroxy-L-proline (2.2) was converted to a key oxazolidinone precursor (2.1) by an improved Greenwood's procedure.47,48 The diastereofacial selective property of (2.1) led to a stereo-controlled 1,3-dipolar cycloaddition and gave a single tricyclic diastereomer (2.20). The N-O bond of the resulting isoxazoline (2.20) was cleaved by a reductive ring-opening, followed by an elimination to give enone (2.26). The enone (2.26) was converted to a b-silanol (2.33) by a nucleophillic addition with LiCH2Si(CH3)3 and then an acetylation to (2.27) was attempted. Addition of Gilman reagent to the enone (2.26) resulting a diastereoselective 1,4-nucleophillic addition and afforded the C-2,C-3 trans, C-3,C-4 cis sterically favoued bicyclic pyrrolidine (2.38) as the only diastereomer. All that remains for the synthesis of kainic acid (1.1) are olefination, ring-opening of carbamate, oxidation and deprotection.