Some Stereochemical Aspects of the Strecker Synthesis and the Bucherer - Bergs Reaction

Abstract

Both the Strecker and Bucherer–Bergs reactions convert the norbornane keto ester methyl bicyclo[2.2.1]hept-6-one-2-endo-carboxylate into the lactam 6-endo-aminobicyclo[2.2.1]heptane-2-endo-carboxylic acid-γ-lactam-6-exo-carboxylic acid. This lactam is unusually stable and cannot be hydrolyzed to the corresponding amino acid. The stereochemistry in the Strecker reaction, in which the amino group is endo, is contrary to that expected from literature precedent. The stereochemistry in the Bucherer–Bergs reaction, in which the amino group is also endo, has been confirmed by X-ray crystallographic analysis of the intermediate spirohydantoin (±)-bicyclo[2.2.1]heptane-2-endo-carboxylic acid-6-spiro-5′-hydantoin.

Photoremovable chiral auxiliary

“…To simplify GC analysis of the mixture of stereoisomers, 40 3m-p were esterified with methanol in the presence of TsOH to the corresponding methyl esters 7m-p (Scheme 4). The absolute stereochemistry of 7 was determined by comparing it with that of the authentic compounds [41][42][43] (ESI ‡). For comparison, the methyl esters 7m-p were also directly produced by treating the Diels-Alder reaction adducts 2a, b with K 2 CO 3 in aqueous methanol.…”

Overview on magnetically recyclable ferrite nanoparticles: synthesis and their applications in coupling and multicomponent reactions

“…156 Since then, signicant amount of the work has been reported in literature for the application of this reaction for the preparation of various racemic as well as chiral a-amino acids, a-amino nitriles and heterocyclic derivatives. [157][158][159][160][161][162][163] Typical mechanism of Strecker synthesis is depicted in Fig. 9.…”

The Bucherer–Bergs Multicomponent Synthesis of Hydantoins—Excellence in Simplicity

“…Because of aqueous reaction conditions, there is no need for dry solvents. Most commonly, a mixture of water with ethanol (or methanol) or methanol itself is employed [ 138 , 139 , 140 , 141 , 142 , 143 , 144 , 145 , 146 , 147 , 148 , 149 , 150 , 151 , 152 , 153 , 154 , 155 , 156 , 157 , 158 , 159 , 160 , 161 , 162 , 163 , 164 , 165 , 166 , 167 , 168 , 169 , 170 , 171 , 172 , 173 , 174 , 175 , 176 , 177 , 178 , 179 , 180 , 181 , 182 , 183 , 184 , 185 , 186 , 187 , 188 ...…”