a-(p-Nitroaryl)alanine and a-(p-nitroaryl)serine alkyl esters are efficiently synthesized via oxidative nucleophilic substitution of hydrogen in nitroarenes with carbanions of protected alanine and serine.Nonproteogenic (unnatural) a-amino acids play an important role in design and synthesis of pharmaceutically interesting molecules, such as peptidomimetics, enzyme inhibitors, and conformationally constrained peptides. 2,3 Hence synthesis of such a-amino acids has recently attracted great attention. 4,5 Particular attention has been directed toward the synthesis of quaternary (a,a-disubstituted) glycine derivatives because they are important components of peptides with special properties. 6 Amongst a variety of quaternary a-amino acids, those bearing a p-nitroaryl substituent in a position are practically unknown, and no direct method of synthesis of such amino acids is reported. According to our knowledge the only reported nitroarylated amino acids were synthesized via base-induced Smiles rearrangement of esters of Nalkyl-N-nitrophenylsulphonyl amino acids 7 or via the Strecker synthesis. 8In this communication we present a general and simple method of synthesis of a-(p-nitroaryl) derivatives of alanine and serine via oxidative nucleophilic substitution of hydrogen (ONSH) in nitroarenes. In our previous papers we have reported that carbanions of 2-phenylalkanenitriles 9 and esters of phenylacetic acid 10 add to nitroarenes in positions para to the nitro group producing anionic s H adducts that are subsequently oxidized by KMnO 4 or DDQ to give the respective nitroarylated nitriles and esters. We expected that similar ONSH procedure with proper carbanionic partners could be applied for the synthesis of nitroarylated amino acids. From a great variety of protected amino acids suitable for generation of carbanions 11,12 we have selected protected alanine and serine esters. For alanine we have chosen the commonly used N-(diphenylmethylene)alanine ethyl ester (1a) 13 and the much less common N-(1,3-dithiolane-2-ylidene)alanine isopropyl ester (1b), readily prepared via the reaction of the ester of alanine, CS 2 and ethylene bromide. 12 As a precursor of the protected serine ester carbanion we have selected 2-phenyl-4-carboethoxy-2-oxazoline (1c). 14 It should be stressed that 1a and 1c have also been widely used for synthesis of a,a-dialkylglycine derivatives via enantioselective phase-transfer-catalyzed (PTC) alkylation. 15,16 Scheme 1 Reagents and conditions: (i) nitroarene (2 equiv), tBuOK (1.5 equiv), THF, DMF, -78 °C; (ii) DDQ (1.2 equiv), -78 °C, then r.t.; (iii) aq HCl, EtOH or H 2 O 2 (10 equiv), HCO 2 H, MeCN, 5 °C to 20 °C.Both of the precursors of alanine carbanions 1a and 1b are sufficiently acidic to be deprotonated by t-BuOK in THF to give carbanions of proper nucleophilicity that add to activated nitroarene rings giving s H adducts that were further oxidized by DDQ to the expected nitroarylated products.Thus treatment of a mixture of nitroarene 2-8 (2 equiv), and carbanion precursor 1a or 1b (1 equiv...