Photochemical Synthesis of Macrocycles

Formation of Six‐Membered (and Larger) Rings

“…In a number of cases, the photochemical synthesis is the method of choice, and occasionally there is no thermal counterpart. It should be noted that the list of reactions included here is not meant to be exhaustive, and additional examples are provided in several related reviews [1,2,41,85,86].…”

4,5,6,7-Tetrachloro-3-(furan-3-yl)-3-hydroxy-2-(3-hydroxypropyl)-2,3-dihydro-1H-isoindol-1-one

“…The construction of medium and large heterocyclic ring systems has constantly been an important task in organic synthesis (Evans & Holmes, 1991;Griesbeck et al, 1996;Illuminati & Mandolini, 1981). Recently, photo-induced intramolecular cyclizations of N-substituted phthalimides have been successfully used for the syntheses of medium-tolarge ring systems.…”

A Ring Expansion Route to Benzofused N‐Heterocycles Through Aryne Insertion into 1,3‐Diaza‐heterocycles

“…[16] Existing methods to synthesize 1,4-benzodiazepines are typically multistep processes. [17] These include cyclization of o-halobenzoic acid derivatives with 1,2-ethylenediamines, [18] o-aminomethylanilines with bis-electrophiles, [19] o-aminobenzophenones with α-amino acid derivatives [20] and the Pictet-Spengler reaction of N-phenyl-1,2-ethylenediamines. [21] Herein we report the development of a new direct route to the synthesis of 2,3,4,5-tetrahydrobenzo-1,4-diazepines that operates via a ring expansion of readily accessible 1,3-diaza-heterocycles.…”