Synthesis of Open‐Chain 2,3‐Disubstituted 4‐nitroketones by Diastereoselective <i>Michael</i>‐addition of (<i>E</i>)‐Enamines to (<i>E</i>)‐Nitroolefins. A topological rule for C, C‐bond forming processes between prochiral centres. Preliminary communication

Abstract

Abstract The Michael ‐additions of aliphatic, alicyclic, and arylsubstituted nitroolefins and enamines lead to γ‐nitroketones 3 in good chemical and excellent (&gt; 90%) diastereomeric yields (see Table 1 ). The known threo ‐configuration of one type of adducts 3 (entries 8, 10, and 11 of Table 1 ) can be arrived at by assuming the approach 8 of the Michael ‐acceptor and ‐donor; the reaction follows a topological rule , which is formulated and which is applicable to such diverse reactions as the diene synthesis, cyclopropanations, carbonyl olefinations and methylenations, aldol‐ and nitroaldol‐type additions, as well as additions of lithium, boron, and chromium derivatives to aldehydes (see 9 , 10 , 11 , and Table 2 ).