Next, we continued our studies under condition B to examine the substrate scope of the In(OTf)3-catalyzed reaction of triazinanes with BCB esters for the synthesis of biscyclobutenyl amines (Scheme 3). This protocol is amenable to a variety of 1,3disubstituted BCB esters, including methyl (5a), ethyl (5b), isopropyl (5c) and benzyl (5d) esters. Notably, the BCB Weinreb amide, which offers potential for further downstream modifications, was also compatible with this transformation (5e 53%). BCB esters bearing various substituents at the para-position of the aryl ring, including alkyl (5f, 5g), phenyl (5h), halide (5i-k) and trifluoromethyl (5l), all participated well in the reaction to afford the target products in 73-99% yields. The structure and relative configuration of 5h were comfirmed by X-ray structure analysis (CCDC 2363143). Furthermore, BCB esters with substituents at the meta-position of the aryl ring, including methyl (5m), methoxy (5n), chloro (5o) and trifluoromethyloxy (5p) that is popular in drugs and agrochemicals, were well-tolerated under the current conditions, providing the aimed products in good yields. Additionally, the reaction proceeded very smoothly with two sterically more demanding ortho-methylphenyl and 2naphthyl BCB esters, and the corresponding products 5q and 5r were isolated in 93% and 97% yields, respectively. The scope of triazinanes was then examined. N-PMB (para-methoxybenzyl) and N-alkyl (isopropyl, cyclopropyl) triazinanes worked well, providing the target products 5s (95%), 5t (32%) and 5u (95%). Notably, the N-propargyl triazinane was also tolerated, and desired product 5v was obtained in 56% yield.