Enantioselective Addition of Activated Terminal Alkynes to 1-Acylpyridinium Salts Catalyzed by Cu−Bis(oxazoline) Complexes
Zhankui Sun, Shouyun Yu, Zuoding Ding, and Dawei Ma*
State Key Laboratory of Bioorganic and Natural Products Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032, China
Abstract. CuI/bis(oxazoline)-catalyzed addition of propiolates and terminal ynones to 1-acylpyridinium salt (generated in situ from reaction of pyridine and methyl chloroformate) affords highly functionalized dihydropyridines with excellent enantioselectivity. It is found that the carbonyl group adjacent to the alkyne moiety is essential for the enantioselectivity of the addition. Short synthesis of indolizidines 167B and 223AB is achieved by employing two addition products.
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