(R,R)-2-t-Butyl-5-methyl-1,3-dioxolan-4-one

Abstract

R,R)[104194- [2][3][4][5][6][7] C 8 H 14 O 3 (MW 158.20) InChI = 1/C8H14O3/c1-5-6(9)11-7(10-5)8(2,3)4/h5,7H,1-4H3/ t5-,7-/m1/s1 InChIKey = LEWYZEQNYWGOBF-IYSWYEEDBC (S,S) [81037-06-1] InChI = 1/C8H14O3/c1-5-6(9)11-7(10-5)8(2,3)4/h5,7H,1-4H3/ t5-,7-/m0/s1 InChIKey = LEWYZEQNYWGOBF-FSPLSTOPBO (cyclic acetals from (R)-and (S)-lactic acid and pivaldehyde; 1b,2-6 reagents for the preparation of enantiopure α-hydroxy-α-methyl carboxylic acids by alkylation of the corresponding lithium enolate with alkyl, 1b,2-4 allyl, 1b,2,7,8 and benzyl 1b halides, by hydroxyalkylation with aldehydes and ketones, 1b,3,9,10 and by Michael addition to nitroalkenes; 9,11 precursor to the 5-bromo derivative used for radical reactions; 12,13 precursor to 2-t-butyl-5methylene-1,3-dioxolan-4-one; 13-15 an acceptor for radical additions; 15,16 and an ene component for Diels-Alder reactions leading to cyclic, heterocyclic, and bicyclic α-hydroxy carboxylic acids 14,17-19 )Physical Data: mp ca. 5 • C; bp 80 • C/20 mmHg; [α] rt D = +44.8 • (c = 1.83, CHCl 3 ) for (S,S)-(1) containing 4% (2R,5S) epimer after two recrystallizations from ether/pentane at −75 • C. Solubility: good to excellent in all common organic solvents. Preparative Method: on a 0.5 mol scale reagent (S,S)-(1) is prepared by condensation of Pivalaldehyde and (S)-lactic acid under acid catalysis in pentane, with azeotropic removal of the water formed. The crude product is distilled in vacuo to give 93% of a 4:1 cis/trans mixture. Two recrystallizations from pentane/ether at −75 • C furnish 60% (S,S)-(1) (cis/trans = 96:4). Handling, Storage, and Precautions: stable for many months under an inert atmosphere in a refrigerator.