Badillo JJ, Ribeiro CJA, Olmstead MM, Franz AK. Titanium(IV)-catalyzed stereoselective synthesis of spirooxindole-1-pyrrolines.
Org Lett 2014;
16:6270-3. [PMID:
25474118 PMCID:
PMC4275133 DOI:
10.1021/ol5028128]
[Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
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A stereoselective
cyclization between alkylidene oxindoles and
5-methoxyoxazoles has been developed using catalytic titanium(IV)
chloride (as low as 5 mol %) to afford spiro[3,3′-oxindole-1-pyrrolines]
in excellent yield (up to 99%) and diastereoselectivity (up to 99:1).
Using a chiral scandium(III)–indapybox/BArF complex affords
enantioenriched spirooxindole-1-pyrrolines where a ligand-induced
reversal of diastereoselectivity is observed. This methodology is
further demonstrated for the synthesis of pyrrolines from malonate
alkylidene and coumarin derivatives.
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