Asymmetrische <i>Michael</i>‐Additionen. Stereoselektive Alkylierung chiraler, nicht racemischer Enolate durch Nitroolefine. Herstellung enantiomerenreiner γ‐Aminobuttersäure‐ und Bernsteinsäure‐Derivate

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<jats:p><jats:bold>Asymmetric <jats:italic>Michael</jats:italic>‐Additions. Stereoselective Alkylation of Chiral, Non‐racemic Enolates by Nitroolefins. Preparation of Enantiomerically Pure γ‐Aminobutyric and Succinic Acid Derivatives</jats:bold></jats:p><jats:p>Chiral, non‐racemic lithium enolates (<jats:bold>E</jats:bold>,<jats:bold>F</jats:bold>,<jats:bold>G</jats:bold>) of 1,3‐dioxolan‐4‐ones, methyl 1,3‐oxazolidin‐4‐carboxylates, methyl 1,3‐oxazolin‐4‐carboxylates, 1,3‐oxazolidin‐5‐ones, and 1,3‐imidazolidin‐4‐ones derived from (<jats:italic>S</jats:italic>)‐lactic acid (<jats:bold>2a</jats:bold>), (<jats:italic>S</jats:italic>)‐mandelic acid (<jats:bold>2b</jats:bold>), and (<jats:italic>S</jats:italic>)‐malic acid (<jats:bold>2c</jats:bold>), or from (<jats:italic>S</jats:italic>)‐alanine (<jats:bold>10</jats:bold>), (<jats:italic>S</jats:italic>)‐proline (<jats:bold>11</jats:bold>), (<jats:italic>S</jats:italic>)‐serine (<jats:bold>12</jats:bold>), and (<jats:italic>S</jats:italic>)‐threonine (<jats:bold>13</jats:bold>), are added to nitroolefins. <jats:italic>Michael</jats:italic> adducts (<jats:bold>3</jats:bold>–<jats:bold>9</jats:bold>, <jats:bold>14</jats:bold>–<jats:bold>18</jats:bold>) are formed (40–80%) with selectivities generally above 90% ds of one of the four possible stereoisomers. Conversions of these nitroalkylated products furnish the α‐branched α‐hydroxysuccinic acids <jats:bold>28</jats:bold> and <jats:bold>29</jats:bold>, the α‐hydroxy‐γ‐amino acid <jats:bold>25</jats:bold>, the α,γ‐di‐amino acid <jats:bold>32</jats:bold>, the substituted γ‐lactames <jats:bold>19</jats:bold>–<jats:bold>22</jats:bold>, and the pyrrolidine <jats:bold>23</jats:bold>. The relative and absolute configuration of the products from dioxolanones and nitropropene are derived by chemical correlation and NOE measurements indicating that the steric course of reaction is to be specified as <jats:italic>1k</jats:italic>, <jats:italic>ul</jats:italic>‐1,3. The mechanism is discussed.</jats:p>

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