Synthetic Approaches to Star-Shaped Molecules with 1,3,5-Trisubstituted Aromatic Cores.

In this report, we summarize various synthetic approaches to star-shaped molecules. To design these highly functionalized molecules, several simple building blocks are assembled via trimerization protocols starting with commercially available starting materials. Later on, these building blocks were synthetically manipulated to generate extended star-shaped molecules. We also presented the syntheses of star-shaped molecules having 2,4,6-trisubstituted-1,3,5-triazine or 1,3,5-trisubstituted benzene rings as a central core and diverse substituted styrene, phenyl, fluorene derivatives at the periphery renders the extended conjugation. Various metal-catalyzed reactions such as Suzuki, Buchwald-Hartwig, Sonogashira, Heck, and Negishi cross-coupling reactions and metathesis were employed to functionalize different star-shaped molecules. Methods described here are helpful to design a wide range of intricate compounds that are valuable in supramolecular chemistry and material sciences. Due to the space limitation, it is not possible to cover all the publications in this area. However, we covered the examples related to star-shaped molecules from our research group and other relevant literature in the recent past. Apart from trimerization sequence, we have made the classification based on the key reactions used in the sequence to prepare star-shaped molecules and higher analogues. Finally, some examples that do not fit in this classification are described as miscellaneous reactions.