A New Method for the Preparation of an Intermediate for the Synthesis Dissertation

A New Method for the Preparation of an Intermediate for the Synthesis of Mycolic Acids - Dissertation Example Nonetheless, the products and the intermediary products remain the same. The Old Method From the old method of synthesis, the mycloni acid is understood to be made form ?-hydroxyl fatty acid that contains long chains of ?-alkyl side chains. These chains often appear has homologous series of the same fatty acids. Notably, they differ by 28 atomic mass units that contains two carbon units as in the case of M. tuberculosis. In the old method of analysis and preparation, the mycolic acids were characterised by hydrophobic C34 to C 65acids with side chains of carbon atoms ranging from C22 to C24 are ? chains. From the old synthesis of mycolic acids, there are three structural mycolic acid classes that are found in the M. tuberculosis . These distinct structures include ?-, keto-, and methoxy-mycolic acids. The ?-mycolic acid forms the highest percentage of approximately seventy per cent and on the other side methoxy and keto-mycolic forms the minor component of the acid mixture. By compos ition, they form approximately 10 to 15 per cent of the mixture. The ?- part of the acid forms the cis and it’s referred to cis-dicyclopropyl fatty acid. This form of fatty acid sets two forms main structural variation. However, it should be noted these structural variations usually depend on source of alpha during the acid synthesis. The variations are usually in terms of terminal alkyl groups while others are in terms of methylene groups. They are found mainly situated between the carboxylic groups and cyclopropane rings. It is worth noting that this arrangement usually makes the ?-mycolic acids from H37Ra strains to test for one group while the other set from Brevanne, PN, C, DT, and Canetti to form other groups. The ?-mycolic acids from clinical strains are usually different from the ?-mycolic from H37Ra strain. Nonetheless, both methoxyl- and keto-mycolic acids have the same structural series especially in their cis- or trans-cyclopropane rings. Experiment 1: Preparation of (S)-Phenylalaninol Procedure S-Phenylalanine (25 g, 303 mmol) was added to a stirred solution of sodium borohydride (14 g, 784.6 mmol) in THF (265 ml). The flask was immersed in a water bath and a solution of fresh concentrated sulphuric acid (13 ml) in ether (35 ml) was added dropwise whilst maintaining the temperature around 20 oC. The reaction was left to stir overnight at room temperature. Methanol (20 ml) was added carefully to destroy any excess NaBH4, followed by addition of sodium hydroxide solution (33 g in 165 ml, 5N) was then added. The reaction mixture was flash distilled to remove any excess solvent (below 100 o C). The residue was then refluxed for 2 h. The turbid aqueous mixture was cooled and filtered, the filtrate and the washings were diluted with water (150 ml) and extracted with CH2CL2 (3x100 ml). The combined organic layers were dried and evaporated to give (S)-phenylaninol which was recrystallized from ethyl acetate and hexane to yield (19.2g, 85%). [?]D18. 5 = -25.3 [literature[?]D18.5-24.7o]43, which showed ?H (400 MHZ, CDCL3): 7.3-7.22 (5H, m ), 3.66 ( 1H, dd, J 3.88, 10.52 Hz), 3.4( 1H, dd, J 7.16, 10.52 Hz), 3.15 ( 1H, m), 2.85 (1H, dd, J 5.28, 13.44 Hz), 2.55 (1H, dd, J 8.52, 13.4 Hz), 1.6 (3H, br, s); ?c : 138.68, 129.22, 128.60, 126.44, 66.45, 54,17, 41.03; Vmax: 3357, 3299, 3129, 3022, 2920, 2877, 2817, 2789, 1579 cm-1.Scheme Discussion The first sequence