Acetylenic molecular architecture

F. Diederich, Functional Acetylenic Molecular Architecture , Pure Appl Chem. 1999, 71, 265. 

Cross-coupling of terminal acetylenes used as nucleophiles with aryl or alkenyl halides (referred to as the Sonogashira-Hagihara, or SH, reaction) is a versatile method of synthesis for acetylenic compounds, which are rapidly gaining importance as advanced new materials and building blocks for implementing unusual molecular architectures. 

The scope of the SH reaction encompasses sp-sp2 (alkenyl, aryl (29),143 heteroaryl) and sp-sp couplings (the modified Cadiot-Chodkiewicz reaction).142 Iodides are most frequently used as electrophilic coupling partners, though the use of bromides, triflates (30),144 or even some reactive chlorides (31)145 is also possible. Due to the low steric bulk of the acetylenic unit, as well as its exceptional ability in the transduction of electronic effects, the SH reaction is well suited for construction of new (e.g., star-like) molecular architectures through polysubstitution (32).146... 

In this section, only enediyne antibiotics bearing an epoxy moiety will be treated. The enediynes are a class of natural products that consist of a unique molecular architecture and exhibit phenomenal antitumor activity. They are stmcturally characterized by an enediyne core containing two acetylenic groups conjugated to a double bond or incipient double bond within a nine-membered ring, such as neocarzinos-tatin 301, or a 10-membered ring, such as dynemicin A 304a. The enediyne cores... 

Polymer electronics, including the use of polymer-nanocomposite-based devices, provide a number of alternative approaches, such as the use of adaptive circuits or the neural network-based processor architectures. Combined with a better understanding of the conductivity mechanism in conjugated polymers such as poly(acetylene) [2, 3] and poly(thiophenes) [4], these factors have initiated this second wave of interest in the low molecular weight organic and polymer-based optoelectronic, electronic and photonic devices. 

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