Total synthesis of antibacterial dibromotyrosine derived alkaloid purpuramine-K

Abstract

The first total synthesis of a dibromotyrosine derived alkaloid purpuramine K <b style="">1</b> reported for possible anti-bacterial activity against gram<i style="">-</i>positive bacteria <i style="">viz:</i> S<i style="">taphylococcus aureus</i>,<i style=""> Bacillus subtilis</i>,<i style=""> Bacillus sphaericus </i>and<i style=""> </i>gram-negative<i style=""> </i>bacteria like <i style="">Chromobacterium violaceum</i>,<i style=""> Klebsiella aerogenes</i>, and <i style="">Pseudomonas aeruginosa </i>has been achieved.<i style=""> </i>The synthesis involves preparation of methyl-3-bromopropyl carbamate <b style="">6</b>, and Boc protected 2-[3,5-dibromo, 4-hydroxy phenyl] ethyl amine <b style="">13</b> which is followed by coupling of these two structural fragments to give corresponding ether <b style="">14</b>.<b style=""> </b>After deprotection of Boc group in compound <b style="">14</b>, it is reacted with 4-hydroxyphenyl pyruvic acid oxime derivative <b style="">17</b> using EDCI/HOBT to give compound <b style="">18</b>, which is further transformed to purpuramine K.<b style=""> </b>