Efficient synthesis of benzyl 2-(S)-[(tert-butoxycarbonyl)amino]-ω-iodoalkanoates

Synthesis of ω-Oxo Amino Acids and trans-5-Substituted Proline Derivatives Using Cross-Metathesis of Unsaturated Amino Acids

“…In our hands, 4 was isolated as a yellow crystalline solid (mp 55-56 °C), as we had previously reported (mp 54-55 °C), 32 rather than as an oil. 31 All other data for 4 matched that reported. …”

“…30 Iodides 4 and 5 were prepared from protected aspartic and glutamic acids by reduction via the mixed anhydride, 31 an improvement on the method using N-hydroxysuccinimide activation, 32 followed by standard conversion of the primary alcohol to the iodide (Scheme 1).…”

Total Synthesis of Isodesmosine by Stepwise, Regioselective Negishi and Sonogashira Cross‐Coupling Reactions

“…[16] Synthesis of 3 or 4 would involve palladium-catalyzed Sonogashira and/or Negishi cross-coupling reactions of trihalogenated pyridines 6 or 7 and the corresponding iodoalkylated l-glycines 8 [16] and 9 [16] or terminal alkyne 10.…”

“…First, the Negishi cross-coupling reaction between 7 and 8 was investigated. The reaction of 2,3,5-triiodopyridine (7) with the pure organozinc reagent derived from γ-iodoalkylated l-glycine 8 [16] was performed by using 4 mol-% Pd-PEPPSI-IPr [21] from 0°C to room temperature for 5 h to afford a trace amount of the desired product 14 (Entry 1). When the reaction was conducted by using 8 mol-% tetrakis(triphenylphosphine)palladium(0) [Pd(PPh 3 ) 4 ], the monocoupled product 14 was obtained in 35 % yield (Entry 2).…”

Improved Negishi Cross‐Coupling Reactions of an Organozinc Reagent Derived from l‐Aspartic Acid with Monohalopyridines

“…For the study of the Negishi cross-coupling reaction, benzyl 2-(S)-(tert-butoxycarbonylamino)-4-iodobutanoate (5) [17] and 3-iodopyridine were chosen as the substrates. The protected amino acid 5 was prepared from commercially available 4-benzoxyl-(S)-3-(tert-butoxycarbonylamino)-4-oxobutanoic acid in two steps.…”