Utilization of [2 + 1] Cycloaddition Reactions of 1-Seleno-2-silylethenes: A Novel Synthesis of 2-Substituted 1-Aminocyclopropane-1-carboxylic Acids

Utilization of [2 + 1] Cycloaddition Reactions of 1-Seleno-2-silylethenes:  A Novel Synthesis of 2-Substituted 1-Aminocyclopropane-1-carboxylic Acid

Lewis Acid-Promoted [2 + 1] Cycloaddition Reactions of a 1-Seleno-2-silylethene to 2-Phosphonoacrylates: Stereoselective Synthesis of a Novel Functionalized α-Aminocyclopropanephosphonic Acid

Stereoselective SnCl4-promoted [2 + 1] cycloaddition reactions of 1-seleno-2-silylethene 1 with 2-phosphonoacrylates 2 lead to highly functionalized cyclopropanephosphonate esters 3 in high yields. The cyclopropane products 3 are potentially versatile starting materials for biologically important compounds. Stereoselective synthesis of a novel functionalized α-aminophosphonic acid derivative, an analogue of (Z)-2,3-methanohomoserine 13, from the cycloadduct 3b was achieved. Stereoselectivity in the [2 + 1] cycloaddition was explained by consideration of the structure of the 2−SnCl4 complex

Lewis Acid Promoted [2 + 1] Cycloaddition Reactions of 1-Seleno-2-silylethene with Tricarbonyl-Substituted Olefins

The reactions of 1-seleno-2-silylethenes 1 with highly electrophilic tricarbonyl-substitued olefins in the presence of Lewis acids have been investigated. The reaction of 1-(phenylseleno)-2-(trimethylsilyl)ethene (1a) with tris(alkoxycarbonyl) olefins 2 or 1,1-bis(alkoxycarbonyl)-2-acyl olefins 3 in the presence of ZnBr2 at −30 °C gave cis-substituted cyclopropanes exclusively. The origin of the cis stereochemistry is ascribed to the synclinal addition path of the ZnBr2-coordinated electrophilic olefin to 1. Application of the highly functionalized selenium- and silicon-substituted cyclopropane products to the preparation of a useful synthetic intermediate 20 for the pyrethroid class of insecticides is also demonstrated

Lewis Acid Promoted [2 + 1] Cycloaddition Reactions of 1-Seleno-2-silylethene with Tricarbonyl-Substituted Olefins

The reactions of 1-seleno-2-silylethenes 1 with highly electrophilic tricarbonyl-substitued olefins in the presence of Lewis acids have been investigated. The reaction of 1-(phenylseleno)-2-(trimethylsilyl)ethene (1a) with tris(alkoxycarbonyl) olefins 2 or 1,1-bis(alkoxycarbonyl)-2-acyl olefins 3 in the presence of ZnBr2 at −30 °C gave cis-substituted cyclopropanes exclusively. The origin of the cis stereochemistry is ascribed to the synclinal addition path of the ZnBr2-coordinated electrophilic olefin to 1. Application of the highly functionalized selenium- and silicon-substituted cyclopropane products to the preparation of a useful synthetic intermediate 20 for the pyrethroid class of insecticides is also demonstrated