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1,3‐Dioxanone Derivatives from β‐Hydroxy‐carboxylic Acids and Pivalaldehyde. Versatile Building Blocks for Syntheses of Enantiomerically Pure Compounds. A Chiral Acetoacetic Acid Derivative Preliminary Communication
Author(s) -
Seebach Dieter,
Zimmermann Jürg
Publication year - 1986
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19860690523
Subject(s) - chemistry , stereocenter , racemization , alkylation , substituent , acetic acid , acetal , enol , cycloaddition , chiral auxiliary , organic chemistry , medicinal chemistry , stereochemistry , enantioselective synthesis , catalysis
( 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 CH 3 substituent (→ 13 ), hydrogenation of the CC bond (→ 1a ) and photochemical cycloaddition (→ 16 ). The overall reactions are substitutions on the one stereogenic center of the starting β‐hydroxy acid without racemization and without using a chiral auxiliary.