Synthesis and Reactivity of 5‐Bromopenta‐2,4‐diynenitrile (BrC₅N): an Access to π‐Conjugated Scaffolds

Abstract

The synthesis of 5‐bromopenta‐2,4‐diynenitrile (BrC5N) in three steps from commercially available compounds is reported. Reacting 5‐bromopenta‐2,4‐diynenitrile with secondary amines led to the formation of stable butadiynamines or enynenitriles, depending on the nature of the amine reactant. The reaction of 5‐bromopenta‐2,4‐diynenitrile with simple terminal alkynes in the presence of secondary amines, copper, and palladium catalysts, provided a straightforward access to original polyfunctional carbon‐rich scaffolds. In this work, different alkynes and secondary amines were tested, which allowed for the preparation of a family of substituted dienes. Given the high synthetic potential of 5‐bromopenta‐2,4‐diynenitrile, we also prepared iodinated counterparts of this compound, that is, 5‐iodopenta‐2,4‐diynenitrile and its lower homologue 3‐iodopropiolonitrile. The UV‐visible spectrum of some relevant compounds was also recorded.

The amphoteric role of nitrogen in the NX2 unit within crystals

“…Other weak interactions were hidden for clarity. The CSD codes are: (i) DBPDZC, 54 (ii) EZIBIA, 55 (iii) HIQYUE, 56 (iv) HIZYIB, 57 (v) REMBUI, 58 (vi) UKIWUH, 59 (vii) UKIXAO 59 and (viii) YARVOE. 60 within group b, presents a larger N → Cl interaction energy, whereas the BEXNAV, also in group b, shows a larger Cl → Cl interaction energy.…”

Synthesis of Conjugated Triynes via Alkyne Metathesis

“…Following the general procedure for the synthesis of chlorinated 4, 114.3, 101.6, 94.4, 18.7, 11.4. Spectral data were consistent with those previously reported. [6] Synthesis of Triisopropyl(penta-1,3-diynyl)silane (13a)…”

“…5 Several methods have been developed to access symmetrical and unsymmetrical triynes. 6 For instance, Tykwinski and co-workers recently reported an elegant synthetic strategy involving a Pd-catalyzed cross-coupling between 3 and various terminal alkynes that lead to the desired triynes 4 (Figure 1, b). 7 Despite the mentioned advances in this field, the development of versatile and efficient methodologies is still necessary.…”

“…Investigations began with the synthesis of diynes 13a-e bearing various substituents following a robust methodology from the literature (Scheme 1). 14 Starting from terminal alkynes 10, the Pd-catalyzed Sonogashira coupling with (E)-1,2-dichloroethylene 11 resulted in the corresponding chloro-enynes 12. The latter was then reacted with n-Buli and iodomethane to produce the expected diynes 13a-e in moderate to good overall yields (Scheme 1).…”

Crystal Engineering of 1-Halopolyynes by End-Group Manipulation

“…Our recent research has been focused on 1-halopolyynes: polyynes that contain at least one halogen end-group. Such compounds exhibit unusual reactivity in, for instance, mechanoactivated coupling with pyrroles, , allow synthesis of amine end-capped polyynes − or might be used in the synthesis of fluorescent dyes . Moreover, 1-halopolyynes are versatile substrates for palladium­(II) , or iridium­(III) end-capped polyynes .…”