1. 'Reverse biomimetic' synthesis of l-arogenate and its stabilized analogues from l-tyrosine
Louise Eagling, Daniel J Leonard, Maria Schwarz, Iñaki Urruzuno, Grace Boden, J Steven Wailes, John W Ward, Jonathan Clayden Chem Sci. 2021 Jul 30;12(34):11394-11398. doi: 10.1039/d1sc03554a. eCollection 2021 Sep 1.
l-Arogenate (also known as l-pretyrosine) is a primary metabolite on a branch of the shikimate biosynthetic pathway to aromatic amino acids. It plays a key role in the synthesis of plant secondary metabolites including alkaloids and the phenylpropanoids that are the key to carbon fixation. Yet understanding the control of arogenate metabolism has been hampered by its extreme instability and the lack of a versatile synthetic route to arogenate and its analogues. We now report a practical synthesis of l-arogenate in seven steps from O-benzyl l-tyrosine methyl ester in an overall yield of 20%. The synthetic route also delivers the fungal metabolite spiroarogenate, as well as a range of stable saturated and substituted analogues of arogenate. The key step in the synthesis is a carboxylative dearomatization by intramolecular electrophilic capture of tyrosine's phenolic ring using an N-chloroformylimidazolidinone moiety, generating a versatile, functionalizable spirodienone intermediate.
2. O-Benzyl-N-tert-butoxycarbonyl-N-methyl-L-tyrosine
Elzbieta Jankowska, Mirosław Gilski, Mariusz Jaskólski, Zbigniew Grzonka, Leszek Łankiewicz Acta Crystallogr C. 2002 Jun;58(Pt 6):o353-4. doi: 10.1107/s0108270102007114. Epub 2002 May 31.
The crystal structure of the title compound, alternatively called 3-[4-(benzyloxy)phenyl]-2-(N-tert-butoxycarbonyl-N-methylamino)propionic acid, C(22)H(27)NO(5), has been studied in order to examine the role of N-methylation as a determinant of peptide conformation. The conformation of the tert-butoxycarbonyl group is trans-trans. The side chain has a folded conformation and the two phenyl rings are effectively perpendicular to one another. The carboxylate hydroxyl group and the urethane carbonyl group form a strong intermolecular O[bond]H...O hydrogen bond.
3. Crystal structure of O-benzyl-l-tyrosine N-carb-oxy anhydride
Aya Inada, Hitoshi Kanazawa Acta Crystallogr E Crystallogr Commun. 2017 Mar 21;73(Pt 4):553-555. doi: 10.1107/S2056989017004236. eCollection 2017 Apr 1.
In the title compound, C17H15NO4 (alternative name; O-benzyl-l-tyrosine N-carb-oxy anhydride), the oxazolidine ring is planer, with an r.m.s. deviation of 0.039 Å. The benz-yloxy and benzyl rings are almost coplanar, making a dihedral angle of 0.078 (10)°, and are inclined to the oxazolidine ring by 59.16 (11) and 58.42 (11)°, respectively. In the crystal, mol-ecules are linked by N-H⋯O and C-H⋯O hydrogen bonds, forming ribbons propagating along [010]. The ribbons are linked by C-H⋯π inter-actions, forming a three-dimensional supra-molecular structure. The oxazolidine rings of adjacent ribbons are arranged into a layer parallel to the ab plane. This arrangement is favourable for the polymerization of the compound in the solid state.