Azidophosphonium salt-directed chemoselective synthesis of (E)/(Z)-cinnamyl-1H-triazoles and regiospecific access to bromomethylcoumarins from Morita–Baylis–Hillman adducts

• Soundararajan Karthikeyan,
• Radha Krishnan Shobana,
• Kamarajapurathu Raju Subimol,
• J. Helen Ratna Monica and
• Ayyanoth Karthik Krishna Kumar

Beilstein J. Org. Chem. 2020, 16, 1579–1587, doi:10.3762/bjoc.16.130

• powerful synthetic tools. Keywords: halomethylcoumarin; Morita–Baylis–Hillman adducts; organocatalyst; phosphonium salt; triazolation; Introduction The presence of versatile functional groups in close proximity classifies Morita–Baylis–Hillman adducts as privileged key scaffolds for synthetic organic

• reactions. We further extended the scope of this transformation to five-membered heterocyclic MBH adducts. To our delight, except pyrroles, the proposed methodology was amenable to MBH adducts of furan and thiophene (3n–q, 70–80%). The mechanistic pathway for the triazolation proceeded via a nucleophilic

• for the synthesis of 3-(bromomethyl)coumarins. Literature-reported cycloaddition reactions of MBH acetates involving azides and alkynes [24][25][26][27][28]. Synthetic methodologies for triazolations of MBH adducts. a) Literature-reported indirect triazolation of MBH adducts [32][33]. b) This work