منابع مشابه
A functionalized enol lactone containing a protected α-amino acid
The crystal structure of N-(3,9-dimethyl-4-phenyl-2,5-dioxo-3,4-dihydro-2H,5H-pyrano[3,2-c]chromen-3-yl)-N-methylbenzamide methanol monosolvate, C(28)H(23)NO(5)·CH(3)OH, has been determined at room temperature by X-ray diffraction. Structural parameters are discussed with reference to ab initio calculations.
متن کامل(1S)-1,2-O-Benzylidene-α-d-glucurono-6,3-lactone
X-ray crystallographic analysis has established that the major product from the protection of d-glucoronolactone with benzaldehyde is (1S)-1,2-O-benzyl-idene-α-d-glucurono-6,3-lactone, C(13)H(12)O(6), rather than the R epimer. The crystal structure exists as O-H⋯O hydrogen-bonded chains of mol-ecules lying parallel to the a axis. The absolute configuration was determined by the use of d-glucuro...
متن کاملStereoselective α-fluoroamide and α-fluoro-γ-lactone synthesis by an asymmetric zwitterionic aza-Claisen rearrangement
BACKGROUND Asymmetric introduction of fluorine alpha-to a carbonyl has become popular recently, largely because the direct fluorination of enolates by asymmetric electrophilic fluorinating reagents has improved, and as a result such compounds are becoming attractive synthons. We have sought an alternative but straightforward asymmetric method to this class of compounds, utilising the zwitterion...
متن کاملAsymmetric Synthesis of Tertiary Alcohols and Thiols via Nonstabilized Tertiary α‐Oxy‐ and α‐Thio‐Substituted Organolithium Species
Nonstabilized α-O-substituted tertiary organolithium species are difficult to generate, and the α-S-substituted analogues are configurationally unstable. We now report that they can both be generated easily and trapped with a range of electrophiles with high enantioselectivity, providing ready access to a range of enantioenriched tertiary alcohols and thiols. The configurational stability of th...
متن کاملOrganocatalytic asymmetric oxy-Michael addition to a γ-hydroxy-α,β-unsaturated thioester via hemiacetal intermediates.
We report an asymmetric oxy-Michael addition to a γ-hydroxy-α,β-unsaturated thioester via hemiacetal intermediates in the presence of Cinchona-alkaloid-thiourea-based bifunctional organocatalysts. This method provides a novel enantioselective route to β-hydroxy carboxyl compounds, which in turn can be used to synthesize valuable chiral building blocks.
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ژورنال
عنوان ژورنال: Berichte der deutschen chemischen Gesellschaft (A and B Series)
سال: 1921
ISSN: 0365-9488
DOI: 10.1002/cber.19210541010