Boron-Catalyzed Azide Insertion of α-Aryl α-Diazoesters

Abstract

A challenging metal-free azide insertion of α-aryl αdiazoesters in the presence of B(C 6 F 5 ) 3 (5 mol %) was developed for the first time. The reaction features an easy operation, wide substrate scope, and mild conditions and affords the corresponding products in moderate to high yields. More importantly, alkene and alkyne functional groups were well tolerated because no cyclopropanation or cyclopropenation was observed. Furthermore, the corresponding azide products could be converted to primary amines or 1,2,3-triazole derivatives after simple transformations.

Triarylborane Catalyzed Carbene Transfer Reactions Using Diazo Precursors

“…Investigations by Tang demonstrated that nucleophilic azides can readily react with diazoesters and undergo azide insertion reactions using catalytic amounts of B(C 6 F 5 ) 3 ( Scheme 14 ). 8 Trimethylsilyl azide (TMSN 3 ) was used as the azide source.…”

Borane-Catalyzed Stereoselective C–H Insertion, Cyclopropanation, and Ring-Opening Reactions

“…In a very similar vein, water could be replaced by azide for this type of nucleophilic substitution, but the mechanism was proposed to proceed through Lewis acid activation of the N 2 functionality. 26 Finally, Prabhu et al have demonstrated the use of catalytic B(C 6 F 5 ) 3 toward C-C bond functionalization of aryl-allyl alcohols using donor-acceptor carbenes, which was suggested to progress through borane activation of the diazo functionality followed by borane-carbene adduct formation. 27 As can be seen above, several different modes of activation of diazo-compounds using B(C 6 F 5 ) 3 have been proposed, and a few computational studies have shed some light on the probable reaction mechanisms.…”

Boron‐Catalyzed Dehydrative Friedel‐Crafts Alkylation of Arenes Using β‐Hydroxyl Ketone as MVK Precursor

“…Our group also observed that α ‐aryl α ‐dizaoesters could undergo O−H bond insertions under the bifunctional catalysis of B(C 6 F 5 ) 3 ⋅ H 2 O complex [13] . Moreover, we reported the first example for azide insertion of α ‐aryl α ‐dizaoesters catalysed by B(C 6 F 5 ) 3 [14] . To continue our reserach interesting, we envisaged that B(C 6 F 5 ) 3 ⋅ H 2 O may be an efficient Brønsted catalyst for dehydration of 4‐hydroxy‐2‐butanone.…”