Methyl Dilithioacetoacetate

Abstract

[30568-00-4] (M1 = M2 = Li+) C5H6Li2O3 (MW 127.99) InChI = 1S/C5H8O3.2Li/c1-4(6)3-5(7)8-2;;/h3,6-7H,1H2,2H3;;/q;2*+1/p-2/b5-3+;; InChIKey = XWAVEVHZAGSWGC-RQCPZROWSA-L [64670-05-9] (M1 = Li+, M2 = Na+) [53437-05-1] C5H6LiNaO3 (MW 144.04) InChI = 1S/C5H8O3.Li.Na/c1-4(6)3-5(7)8-2;;/h3,6-7H,1H2,2H3;;/q;2*+1/p-2/b5-3+;; InChIKey = YWLCQBRPKRXSOW-RQCPZROWSA-L InChI = 1/C5H8O3.Li.Na/c1-4(6)3-5(7)8-2;;/h3,6-7H,1H2,2H3;;/q;2*+1/p-2/b5-3+;;/fC5H6O3.Li.Na/h6-7h;;/q-2;2m InChIKey = YWLCQBRPKRXSOW-IZBMSSKRDN (four-carbon chain, all four carbons of which can be reacted regioselectively; versatile starting material in synthesis of complex molecules; undergoes γ-alkylation and γ-acylation) Solubility: sol THF, ether, dimethoxyethane, and HMPA; slightly sol hydrocarbon solvents. Form Supplied in: generated in situ. Analysis of Reagent Purity: NMR spectroscopy or mass spectrometry of D2O quench.1 Preparative Methods: dianion 1 is prepared in a dry solvent, usually THF or diethyl ether, by adding the β-keto ester to 1.1 equiv of Sodium Hydride, which has been washed free of mineral oil, and then adding 1.05 equiv of n‐Butyllithium at 0 °C (eq 1).1 It may also be prepared by treating the β-keto ester with 2.0 equiv of Lithium Diisopropylamide or Lithium 2,2,6,6‐Tetramethylpiperidide at 0 °C.1 These methods may be used to generated the dianions of a wide range of β-keto esters. The dianion 1 may be quenched with D2O and the degree of dianion formation determined by integration of the 1H NMR methyl peak at δ 2.2 relative to the ester signal or by mass spectrometry.1 Occasionally it is necessary to add HMPA to dissolve the dianions of more substituted β-keto esters. (1) Handling, Storage, and Precautions: generated in solution; stable for hours at 0 °C; reacts with moisture and oxygen.