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Stoeckli-Evans, Helen
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Synthesis of α,β'- and β,β'-linked dimethoxycarbonyldipyrromethanes by Rothemund-type condensation
2012-7-15, Journot, Guillaume, Stoeckli-Evans, Helen, Neier, Reinhard
The Rothemund-type condensation of methoxycarbonylpyrrole with acetone produces mainly the α,β'-linked dipyrromethane, a building block for the synthesis of N-confused macrocycles. The influence of the reaction conditions on the regioselectivity of the process is reported. The x-ray structures of the α,α'-, α,β'- and β,β'-linked dipyrromethanes show an interesting discrimination of the structurally different types of hydrogen bonds. [on SciFinder(R)]
Rac-(2R*,3R*)-S-Ethyl-4-Chloro-3-Hydroxy-2-Phenylbuthanethioate and Rac-(2R*,3R*)-S-Ethyl-2-Phenyl-3-(tosyloxy)buthanethioate: Dichotomy of the Stereoselectivity of the Mukaiyama Reaction
2010, Vallat, Olivier, Buciumas, Ana-maria, Neier, Reinhard, Stoeckli-Evans, Helen
The compds., rac-(2R*,3R*)-S-ethyl-4-chloro-3-hydroxy-2-phenylbuthanethioate (I) and rac-(2R*,3R*)-S-ethyl-3-hydroxy-2-phenylbuthanethioate (II), were prepd. by the Mukaiyama crossed aldol reaction between the silyl enol ether of S-Et 2-phenylethanethioate and simple aldehydes, like 2-chloroacetaldehyde (for I) and acetaldehyde (for II). The stereoselectivity of the Mukaiyama aldol reaction has switched from a syn selective process for the reaction using 2-chloroacetaldehyde to an anti selective process for the reaction with acetaldehyde. [on SciFinder(R)]