24 h. [a] Pd-PEPPSI-IPentCl (2 mol%); [b] Pd-PEPPSI-IPent (2 mol%) and NaOtBu (200 mol%)
[c] NaOtBu (200 mol%)
The optimized reaction condition was found to be general for a variety of anilines and
aliphatic amines. Initially we performed the amination of 4-(4-bromophenyl)thiazole 1a. Simple
aniline was found to work better with only 2 mol% of Pd-PEPPSI-IPentCl resulting in the desire
product 3a in 89% isolated yield. A similar high reactivity was found with o-toluidine resulting in
the product 3b in 98% yield. Electron rich anilines, o-anisidine and m-anisidine were highly
reactive and worked well with only 2 mol% of Pd-PEPPSI-IPent catalyst, resulting in products 3d
and 3e each in 96% yields. p-Anisidine in the standard condition gave product 3f in quantitative
yield. Subsequently, we look in to electron poor aniline in anticipation that they will show slightly
lower conversion. On the contrary, chloro and fluoro substituted anilines works well and resulted
in excellent yields. o-Chloroaniline, p-chloroaniline and 2,4-dichloroaniline resulted in product
3g, 3h and 3i in 99%, 99% and 90% yields respectively. p-Fluoroaniline gave the product 3j in
97% isolated yield. In addition, 3-(trifluoromethyl)aniline resulted in products 3k in 98% yield.
When a N-substituted aniline, N-Methylaniline was treated in similar conditions, the tertiary
aniline 3l was formed in 78% yield. Similarly, aliphatic amines were found to be good coupling
partners, even with Pd-PEPPSI-IPr as a catalyst. N-Methylbenzylamine and morpholine were
proved to be nice coupling counterparts in this system, yielding the desired coupled products 3m
and 3n in range of 85-88%, while with Pd-PEPPSI-IPent as a catalyst, the reaction gave the cross
coupled products in nearly quantitative yields. n-Butylamine behaved different in comparison to
the other aliphatic amine as utilizing PEPPSI-IPr catalyst it led to desired coupled product in just
15% yield but changing the catalyst system to Pd-PEPPSI-IPentCl, it furnished the cross coupled
product 3o in 79% yield (Table 3).
The scope of the reaction was further explored using phenyl substituted thiazole substrate 1b,
which was used to cross coupled with electron rich and electron deficient anilines as well as
aliphatic amine counterparts, demonstrating the generality and efficiency Pd-PEPPSI catalysis for
C-N bond forming reaction. Therefore, when 1b was cross coupled with p-toluidine, the product
3p was isolated in 92% yield. Furthermore, 4-flouroaniline and 3-triflouromethylaniline led to the
desired products 3q and 3s in 82% and 89% yield respectively. Other amines such as N-
methylaniline, N-methylbenzylamine and morpholine were also successfully coupled furnishing
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