Silicon in benzamide directed ortho metalation reactions synthesis of peri-methyl substituted PAHs and natural anthraquinones

✍ Scribed by R.J. Mills; V. Snieckus

• Publisher: Elsevier Science
• Year: 1984
• Tongue: French
• Weight: 181 KB
• Volume: 25
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(00)99916-7

✦ Synopsis

The n,a-bis(trimethylsilvl)-o-toluamides 4 and 2, systems protected from benz.ylic deprotonation, are available startinq iiiaterials for%the short syntheses of peri-methyl substituted benz[a]anthraquinones $,a_ respectively. and 3 and desoxverythrolaccin trimethyl ether ,I$, The recent demonstration1 of alternate benzamide directed metalation2 reactivity b,v silicon protection (J and 2) expands the utility of this methodoloqy for the syntheses of polysubstituted aromatics. In this Letter, we delineate a potential qeneral strateqy 2 + 3 -* q, for the construction of peri-methyl substituted polycyclic aromatic hydrocarbon (PAHs) carcinogens3 and naturally occurrinq anthraauinones.4 We illustrate this approach by short and efficient syntheses of benz[a]anthraquinones 2 and z and desox,yerythrolaccin trimethyl ether 12. In the accompanyinq Letter5, we describe how the above strateqy with compounds of ?/L the type 1, coupled with F--or Br+-induced desilylations achieve similar synthetic ?I advantages.