10.1039/c2cc31394d
The study investigates the behavior of thioamides under Kulinkovich-type conditions and compares it with that of carboxylic amides. The main chemicals involved are thioamides (such as 1aS, 1bS, 1cS, etc.) and carboxylic amides (such as 1aO, 1bO, 1cO, etc.), which serve as the starting materials for the reactions. Alkoxytitanium(IV) species like Ti(OiPr)4 are used as reagents to mediate the transformations. Grignard reagents, including cyclopentylmagnesium chloride and cyclohexylmagnesium chloride, play a crucial role in the reactions. The study finds that thioamides exhibit dramatically different behaviors from carboxylic amides under these conditions. For instance, while carboxylic amides typically undergo intramolecular Kulinkovich–de Meijere reactions to form cyclopropylamines, thioamides can also undergo reductive alkylation processes to form tertiary amines, with the initially formed titanacyclopropane reacting faster with thioamide functions than with alkene groups. The researchers propose a mechanism involving the formation of a thia-titanacyclopropane intermediate, which can be trapped intramolecularly by an olefin group or lead to the production of secondary amines through a competitive pathway.
10.1055/s-2004-835663
The study presents a novel methodology for synthesizing N-diphenylmethylene-2-vinyl-substituted cyclopropylamines, which are significant in pharmaceuticals and natural products due to their biological activity. The synthesis begins with allylsulfones, specifically compound 11, which can be obtained in both enantiomeric forms. The researchers utilized various chemicals, including base treatments for allylsulfones to form trans:cis cyclopropanols, and molecular modeling to study the stereoselectivity of cyclopropane formation. The study also involved the use of Garner’s aldehyde, a key intermediate in synthesizing biologically active compounds, and the transformation of amino alcohols into cyclopropylamines with the help of protecting groups like Tosyl, Boc, Moc, and benzyl. The purpose of these chemicals was to achieve high diastereoselectivity in the synthesis of chiral amino-cyclopropanes, which are valuable as building blocks for the synthesis of conformationally restricted amino acids. The study's innovative approach and findings contribute to the field of asymmetric synthesis, particularly for cyclopropylamines.
F, 
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