Synthesis of a New Constrained Homoserine

Free-Radical Reactions in the Synthesis of α-Amino Acids and Derivatives

“…Often free-radical reductions with tributyltin hydride are used to remove a functional group that has been incorporated in an amino acid derivative as part of an overall synthetic strategy. Accordingly, reactions of the derivatives of nitrovaline 207 and nitroleucine 208 were used to substitute the nitro group for hydrogen, in syntheses of amino acid derivatives using alkyl nitronates. , Xanthate transfer cyclizations and addition reactions have been used in the synthesis of amino acid derivatives, as discussed in more detail below, and reductive cleavage of the product xanthates has been exploited to increase the utility of these processes. , Iodides have been reduced with tributyltin hydride, as part of syntheses of constrained hydroxy amino acid derivatives, − while tris(trimethylsilyl)silane has been exploited in a similar manner for the synthesis of bicyclic amino acid derivatives …”

“…68,129 Xanthate transfer cyclizations and addition reactions have been used in the synthesis of amino acid derivatives, as discussed in more detail below, and reductive cleavage of the product xanthates has been exploited to increase the utility of these processes. 218,219 Iodides have been reduced with tributyltin hydride, as part of syntheses of constrained hydroxy amino acid derivatives, [220][221][222] while tris(trimethylsilyl)silane has been exploited in a similar manner for the synthesis of bicyclic amino acid derivatives. 223 Barton esters of aspartate and glutamate derivatives have been used to remove side-chain carboxyl groups.…”

Synthesis of constrained analogues of tryptophan

“…Reported [4 + 2] cycloaddition reactions of methyl 2-acetamidoacrylate ( 2 ) and its congeners with cyclic/acyclic dienes and azadienes occur under conventional heating or microwave irradiation [ 24 ]. Moreover, the use of titanium tetrachloride as Lewis acidic promoter has been reported [ 25 ]. Finally, simple functionalization reactions of indoles with 2 are reported in the literature [ 26 – 29 ].…”

Validation of missed space-group symmetry in X-ray powder diffraction structures with dispersion-corrected density functional theory

“…As written earlier (van de Streek & Neumann, 2010), possible explanations include weakly scattering crystals, a problem in the measurement, unresolved disorder, unusually high or strongly anisotropic thermal expansion, or simply errors in the crystal structure determination, such as wrong assignment of atoms. For eight of these structures [CADPON (Tomioka et al, 2001), HITNED (Marek et al, 1995), HOSJUU (Mitsukura et al, 1999), IBPBAC (Leadbetter et al, 1980), KUSLUF ( Nakano et al, 1992), LULSUH (Chang et al, 2009), RIGSEF (Avenoza et al, 1997), YEYNAR (Aqad et al, 1994)] the space group after energy minimization is the correct higher space group, for ten structures [BAGPII (Dupont et al, 1981), FEXCOA (Wang et al, 1987), GOMKAU (Lehmann et al, 1999), HALJUZ (De Ridder et al, 1993), KORZIA (Andreetti et al, 1991), RUHJAF (Schreiner & Pruckner, 1997), TANROP (McKenna et al, 1992), TEBLUH (Pan et al, 1996), TIWXOM (Karle et al, 1996), UWUFEY (Sun et al, 1996)] the space group after energy minimization does not match the higher space group. These 18 structures are excluded from further analysis.…”