FSO₂N₃-Enabled Synthesis of Tetrazoles from Amidines and Guanidines

Abstract

Herein we report the facile syntheses of tetrazoles enabled by FSO2N3 under mild conditions. FSO2N3 has been shown as the most powerful diazotizing reagent, which converts thousands of primary amines to azides fast and orthogonally. As the follow-up studies of the diazo transfer reaction using FSO2N3, we discover that amidines and guanidines are rapidly transformed into tetrazole derivatives when reacting with FSO2N3 under an aqueous environment, which is unprecedented for tetrazole synthesis.

Catalytic Tetrazole Synthesis via [3+2] Cycloaddition of NaN3 to Organonitriles Promoted by Co(II)-complex: Isolation and Characterization of a Co(II)-diazido Intermediate

“…With growing interest toward the development of novel tetrazole derivatives, several synthetic methods have evolved. − In particular, the [3+2] cycloaddition of azide with organic nitrile has been the most proficient route to 5-substituted 1H-tetrazoles. − To minimize the high activation barrier associated with the cycloaddition reactions, several homogeneous − and heterogeneous − catalysts and additives have been used. Many of those involve the use of expensive and toxic metals, − strong Lewis acids, − and mediated via highly explosive and toxic hydrazoic acid. , Although transition metal salts have been widely used to catalyze the synthesis of 5-substituted 1H-tetrazoles via dipolar cycloaddition, − use of metal complex catalysts is relatively limited .…”

“… 31 − 34 In particular, the [3+2] cycloaddition of azide with organic nitrile has been the most proficient route to 5-substituted 1H-tetrazoles. 35 − 37 To minimize the high activation barrier associated with the cycloaddition reactions, several homogeneous 38 − 41 and heterogeneous 42 − 46 catalysts and additives have been used. Many of those involve the use of expensive and toxic metals, 47 − 51 strong Lewis acids, 52 − 56 and mediated via highly explosive and toxic hydrazoic acid.…”

Base‐Regulated Synthesis of the Bestmann‐Ohira or Seyferth‐Gilbert Reagent Utilizing FSO2N3

“…Recently, FSO 2 N 3 was also demonstrated to convert amidines and guanidines to the corresponding tetrazoles. [15] One benefit of using FSO 2 N 3 for diazotransfer is that the hydrolysis of FSO 2 NH 2 to sulfamic acid (HOSO 2 NH 2 ) and aqueous fluoride in aqueous basic condition through a SuFEx fashion provides more driving forces to the diazotransfer step, which was absent for other sulfonyl azides. With the continuing interest in FSO 2 N 3 as a superior diazotizing reagent and new methodologies to synthesize alkynes for CuAAC click reactions, herein we report the use of FSO 2 N 3 for diazotizing a series of activated methylene compounds to deliver the corresponding diazo products.…”