107289-11-2Relevant academic research and scientific papers
128. α-Alkylierung von β-Hydroxycarbonsaeuren ueber 1,3-Dioxan-4-on-Enolate. Highly Diastereoselective α-Alkylation of β-Hydroxycarboxylic Acids Through Lithium Enolates of 1,3-Dioxan-4-ones
Zimmermann, Juerg,Seebach, Dieter,Ha, Tae-Kyu
, p. 1143 - 1155 (1988)
From serine, β-hydroxyisobutyric acid ("Roche" acid) and β-hydroxybutyric acid, the dioxanones 1-6 were prepared.The generation of the enolates of type 1 with LDA at -75 deg C and alkylation gave products with trans-configuration whereas protonation of the 5-methyl-substituted enolate allowed access to the cis-configurated β-hydroxybutyric-acid derivative 12.Hydrolysis gave the free β-hydroxy acids of "syn"- and "anti"-configuration.Alkylation of the 6-unsubstituted dioxanones 1 and 3 yielded predominantly products resulting from attack in the cis-position of the t-Bu group.The "reactive" conformation of the enolates involved is tentatively derived from the product configuration.The selectivity of the alkylation is also discussed in terms of the results of an ab-initio calculation on the enolates M-P.
(E,R,R)-5-Alkylidene-2-tert-butyl-6-methyl-1,3-dioxan-4-ones: Preparation from (R)-3-Hydroxybutbutyric Acid, Cuprate Additions and Hydrolyses to 3-Hydroxycarboxylic Acids with Chiral Secondary Alkyl Substituents in the 2-Position
Amberg, Willi,Seebach, Dieter
, p. 2413 - 2428 (2007/10/02)
Li enolates of (R,R)-2-tert-Butyl-6-methyl-1,3-dioxan-4-one add to aliphatic or aromatic aldehydes with relative topicity Re,Re (2:1 to 10:1, 9 examples).The title compounds are obtained from these aldol adducts by dehydration through mesylates (5 example
123. 1,3-Dioxanone Derivatives from β-Hydroxy-carboxylic Acids and Pivalaldehyde. Versatile Buiding Blocks for Syntheses of Enantiomerically Pure Compounds. A Chiral Acetoacetic Acid Derivative
Seebach, Dieter,Zimmermann, Juerg
, p. 1147 - 1152 (2007/10/02)
(R)-3-Hydroxybutyric acid (from the biopolymer PHB) and pivalaldehyde give the crystalline cis- or (R,R)-2-(tert-butyl)-6-methyl-1,3-dioxan-4-one (1a), the enolate of which is stable at low temperature in THF solution and can be alkylated diastereoselectively (->3, 4, 5, and 7).Phenylselenation and subsequent elimination give an enantiomerically pure enol acetal 10 of aceto-acetic acid.Some reactions of 10 have been carried out, such as Michael addition (->11), alkylation on the CH3 substituent (->13), hydrogenation of the C=C bond (->1a) and photochemical cycloaddition (->16).The overall reactions are substitutions on the one sterogenic center of the starting β-hydroxy acid without racemization and without using a chiral auxiliary.
