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I. Synthesis and Application of N-Silyloxy Enamines II. Helquats: Synthesis and Properties
Sonawane, Manoj Rambhau ; Teplý, Filip (advisor) ; Dvořák, Dalimil (referee) ; Veselý, Jan (referee)
1. Abstract The work reported in this thesis is divided into two parts. In the first part, the chemistry of N-silyloxy enamine is discussed. The introductory section contains a brief overview of enamines, N,N-bis(silyloxy)enamines and N-silyloxy enamines, including their preparation, reactivity as well as comparison of their nucleophilicity with enolates and silyl enol ethers. Enamines in aldol reactions and synthetic challenges of asymmetric cross-aldol reactions are briefly discussed. The results and discussion section describes the synthesis of N-silyloxy enamines derived from aldehydes and use of N-(trimethylsilyloxy)enamines as new aldehyde enolate synthons for general, efficient and diastereoselective aldol-type reaction with dimethyl acetals and ketals. Also the syn-diastereoselectivity in β-methoxy nitrone products and their conversion to respective β-methoxy aldehydes is mentioned. Furthermore, synthesis of N-methyl-N-(trimethylsilyloxy)enamines from ketones is reported. In the second part, synthesis of new symmetric and non-symmetric helquats is reported. In the introductory section a brief overview of N-heteroaromatic cations including their natural occurrence and synthetic aspects as well as their applications in organocatalysis, molecular biology is discussed. Helicenes, viologens,...
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I. Synthesis and Application of N-Silyloxy Enamines II. Helquats: Synthesis and Properties
Sonawane, Manoj Rambhau ; Teplý, Filip (advisor) ; Dvořák, Dalimil (referee) ; Veselý, Jan (referee)
1. Abstract The work reported in this thesis is divided into two parts. In the first part, the chemistry of N-silyloxy enamine is discussed. The introductory section contains a brief overview of enamines, N,N-bis(silyloxy)enamines and N-silyloxy enamines, including their preparation, reactivity as well as comparison of their nucleophilicity with enolates and silyl enol ethers. Enamines in aldol reactions and synthetic challenges of asymmetric cross-aldol reactions are briefly discussed. The results and discussion section describes the synthesis of N-silyloxy enamines derived from aldehydes and use of N-(trimethylsilyloxy)enamines as new aldehyde enolate synthons for general, efficient and diastereoselective aldol-type reaction with dimethyl acetals and ketals. Also the syn-diastereoselectivity in β-methoxy nitrone products and their conversion to respective β-methoxy aldehydes is mentioned. Furthermore, synthesis of N-methyl-N-(trimethylsilyloxy)enamines from ketones is reported. In the second part, synthesis of new symmetric and non-symmetric helquats is reported. In the introductory section a brief overview of N-heteroaromatic cations including their natural occurrence and synthetic aspects as well as their applications in organocatalysis, molecular biology is discussed. Helicenes, viologens,...
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Capillary electrophoresis applied to chiral analysis of helquats and characterization of their intermediates and interconversion barriers using randomly and single isomer sulfated cyclodextrins as stereoselectors
Kašička, Václav ; Koval, Dušan ; Sázelová, Petra ; Severa, Lukáš ; Vávra, Jan ; Adriaenssens, Louis ; Sonawane, Manoj R. ; Teplý, Filip
Capillary electrophoresis in acidic sodium phosphate background electrolyte, pH 2.4, with randomly sulfated alfa-, beta- and gamma-cyclodextrins as chiral selectors was applied to fast, high-resolution separation of enantiomers of a series of 35 helquats, a new class of N-heteroaromatic dicationic helicene-like species. The developed methodology was employed for evaluation of preparative enantioresolution procedures of helquats, for monitoring their racemization and for determination of interconversion barrier of helquat enantiomers.
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