Synthesis and Reactivity of Cyclic Borane‐Amidine Conjugated Molecules Formed by Direct 1, 2‐Carboboration of Carbodiimides with 9‐Borafluorenes. Issue 10 (19th February 2019)

• Record Type: Journal Article
• Authors: Kashida, Junki; Shoji, Yoshiaki; Fukushima, Takanori
• Is Part Of: Chemistry, an Asian journal. Volume 14:Issue 10(2019)
• Page Start: 1879
• Page End: 1885
• Publication Date: 2019-02-19
• Subjects: amidines -- borafluorenes -- carboboration -- carbodiimides -- heterocycles; Chemistry -- Periodicals; 540.5
• DOI: 10.1002/asia.201900047
• Languages: English
• ISSNs: 1861-4728

Abstract

Abstract: Efficient 1, 2‐carboboration reactions to the C=N bond of carbodiimides with 9‐borafluorenes, which give rise to cyclic borane‐amidine conjugates with a seven‐membered BNC5 ring, are reported. The resulting cyclic borane‐amidine conjugates can be hydrolyzed into an acyclic bifunctional biaryl compound carrying both boronic acid and amidine groups, rendering the utility of the two‐step protocol for the synthesis of multi‐functionalized molecular systems with a potential as a supramolecular building block. Furthermore, the conjugated structure of the cyclic boron‐amidine compounds can be changed upon alkylation of the boron atom that increases the coordination number of boron. The combination of Lewis acid (borane) and conjugated base (amidine) provides rich structural diversity of heteroatom‐containing π‐conjugated systems. Abstract : NBC News : Direct 1, 2‐carboboration of carbodiimide by 9‐borafluorenes afforded heterocyclic compounds with a BNC5 ring. The conjugated structure of the BNC5 ring can be altered by changing the coordination number of boron. Upon hydrolysis, ring‐opening of the BNC5 ring took place to give a bifunctional biaryl carrying boronic acid and amidinium functionalities, demonstrating the utility of 1, 2‐carboboration for the construction of multi‐functional building blocks (e.g., for supramolecular assemblies).