Annulenes 18 annulene trisulfide

In 1964, Badger and coworkers described what was the first representative of a new class of heteroatom-bridged [18]annulenes. This they did with their report on the synthesis of the so-called [18]annulene trisulfide 2.335 (Figure 2.3.4). ° Macrocycle 2.335 represents just one of ten possible macrocycles (i.e., 2.335-2.344) of this type that could in theory be derived by formally substituting one, two or all three of the thiophene subunits with pyrrole and/or furan. Indeed, since the initial report of... 

Tn addition to the cyclotetramer 4.171, a significant yield (16%) of the cyclotrimeric [18]annulene trisulfide (discussed in Chapter 2) was obtained. Also generated, albeit in lower yields (on the order of 1-1.5%), were two isomeric cyclopentamers (Chapter 6) and two isomeric hexamers (Chapter 7). This reaction affords a 1.3% yield of a cyclic hexamer. This product is discussed in Chapter 7. 

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