Photoassisted Access to New Polyheterocycles.

摘要

Photoassisted diversity-oriented synthesis holds great promise in its ability to provide rapid access to complex and diverse molecular scaffolds. As it stands, while photochemical techniques have this potential, their implementation in the field of synthetic organic chemistry is very limited. The main goal of this project was to utilize photochemically assisted techniques in the synthesis of a variety of novel polyheterocycles.;Initially, we explored the how the strain installed in these polycycles could be harnessed to trigger cationic rearrangements in the framework of the system. This was achieved via the high yield and rapid assembly of a highly strained system containing two oxetanes. This bis-oxetane was derived from a compound containing carbonyl groups endo- to two respective bicyclic olefins which was assembled via a simple Diels-Alder step. The oxetanes were formed in a Paterno-Buchi reaction via excited-state chemistry. The protolytic ring-opening of this bis-oxetane compound afforded two highly unusual polycyclic products that both result from rather complex mechanisms which are proposed in this work. In addition, we were able to elaborate on this rapid Diels-Alder assembly motif by designing a double-tandem [4+2][2+2][4+2][2+2] synthetic sequence which culminates in a complex scaffold containing an oxetane. When subjected to acidolysis, this oxetane affords a complex polycycle with rigidly held pendants rich in heteroatoms.