1. Anthracene-1-carboxylic acid
L J Fitzgerald, R E Gerkin Acta Crystallogr C. 1997 Aug 15;53 ( Pt 8):1080-2. doi: 10.1107/s0108270197004927.
The title compound, C15H10O2, was found to crystallize in the centrosymmetric space group P2(1)/n. The hydrogen bonding is of the cyclic dimer type about a center of symmetry. The carboxyl O atoms are ordered as is the carboxyl H atom. The anthracene core, while less nearly planar, shows good agreement with the anthracene cores of anthracene-9-carboxylic acid and anthracene-1,6-dicarboxylic acid. The carboxyl group plane makes a dihedral angle of 12.4 (2) degrees with the best-fit anthracene core plane.
2. 1-(o-tolylmethyl)naphthalene-2-carboxylic acid
R E Gerkin Acta Crystallogr C. 1998 Dec 15;54 ( Pt 12):1885-7. doi: 10.1107/s0108270198009214.
The title acid, C19H16O2, crystallized in space group P1. In this structure, a hydrogen bond of the 'cyclic dimer' type is formed about a center of symmetry. The O(donor)...O(acceptor) distance is 2.647 (1) A. The carboxylic H and O atoms are ordered. The dihedral angle between the best-fit naphthalene plane and the carboxylic acid group plane is 11.1 (2) degrees.
3. Synthesis of 1-Boc-3-fluoroazetidine-3-carboxylic acid
Eva Van Hende, Guido Verniest, Frederik Deroose, Jan-Willem Thuring, Gregor Macdonald, Norbert De Kimpe J Org Chem. 2009 Mar 6;74(5):2250-3. doi: 10.1021/jo802791r.
Synthetic strategies toward 3-fluoroazetidine-3-carboxylic acid, a new cyclic fluorinated beta-amino acid with high potential as building block in medicinal chemistry, were evaluated. The successful pathway includes the bromofluorination of N-(diphenylmethylidene)-2-(4-methoxyphenoxymethyl)-2-propenylamine, yielding 1-diphenylmethyl-3-hydroxymethyl-3-fluoroazetidine after reduction of the imino bond, ring closure, and removal of the 4-methoxybenzyl group. Changing the N-protecting group to a Boc-group allows further oxidation to 1-Boc-3-fluoroazetidine-3-carboxylic acid, a new fluorinated heterocyclic amino acid.
