Diastereoselective alkylation of acetoacetates of chiral inductors. Synthetic applications

Abstract

Diastereoselective alkylations of acetoacetates of chiral inductors are reviewed. The formed products are starting materials for the preparation of enantiomerically pure amino acids, 4,4‐disub‐stituted 2‐pyrazolin‐5‐ones, and of oxazoles and pyrazoles incorporating the chiral inductors.

The Contribution Made by Triphenylphosphane in the Putative Catalysis by Ruthenium Species in Conjugate Additions of β-Dicarbonyl Compounds

“…This stereochemical preference is the same as that previously described for the same chirality inductor in conventional alkylations of 1e. [24,25] We assume the same stereochemical behavior in assigning configurations to diastereoisomers 13eb and 14eb. The reaction between 1f and 2e, when catalyzed by triphenylphosphane at room temp, afforded a better yield of addition products 13fe and 14fe in excellent de (run 5).…”

“…Again, assignment of configuration to the major and to the minor diastereoisomers was made by analogy with previous alkylations of (4S)-N-(3Ј-oxobutanoyl)-4-benzyloxazolidin-2-one. [25] Ketoamide 1g was inert towards acrylonitrile (2f) and ethyl acrylate (2g) in the presence of ruthenium hydride. Scheme 4 The 2-methylacetoacetate of -ribonolactone acetonide (1h) is a more versatile substrate than 1f or 1g.…”

“…Further transformations on the acetyl group and on the primary ester permitted the preparation of optically pure α,α-disubstituted glycines. [25,26] We therefore undertook an exploration of the conjugate additions of 1h under ruthenium catalysis and triphenylphosphane catalysis conditions (Table 4 and Scheme 5). Even though the des were moderate or low, the reactivity of 1h is remarkable in terms of chemical yields and broad range of electrophiles.…”

Synthesis of 2-(dibenzosuberen-5-yl)-1,3-dicarbonyl compounds

“…The developed approach towards dibenzosuberenyl fragment introduction into 1,3-dicarbonyl compounds under the catalysis with Lewis acids is a convenient alternative to the described before acid-catalyzed reaction of this type [9,10]. EXPERIMENTAL 1 H and 13 C NMR spectra were registered on an ECA400 instrument (JEOL) in CDCl 3 (Aldrich) or in (CD 3 ) 2 SO (Deutero GmbH); tetramethylsilane by Aldrich was used as a reference.…”

“…Thus, 2-(dibenzosuberen-5-yl)indane-1,3-dione inhibits some enzymes [4][5][6] and can be used as a starting compound for the synthesis of various derivatives due to the presence of 1,3dicarbonyl fragment, which possesses a great synthetic potential [7,8]. Apart the above mentioned derivative of 1,3-indanone only few representatives of 1,3-dioxo compounds like (dibenzosuberenyl)malonic acid [9] and N- [2-(dibenzosuberen-5-yl)acetoacetyl]-4-benzyloxazolidin-2-one [10] are known.…”