An Efficient Method for Synthesis of N-tert-Butyl Amides Using Oxalic Acid Dihydrate in Solvent-Free Condition
Table 1
Amidation of tert-butylacetate or tert-butanol with nitriles using oxalic acid dehydrate.
Entry
Substrate
Nitrile
Amidea
Time/h
Yield %b
(CH3)3COAc
C6H5CN
C6H5CONHtBu
2
90
(CH3)3COH
C6H5CN
C6H5CONHtBu
2.30
88
(CH3)3COAc
p-Cl-C6H4CN
p-Cl-C6H4CONHtBu
2
92
(CH3)3COH
p-Cl-C6H4CN
p-Cl-C6H4CONHtBu
3
90
(CH3)3COAc
p-Me-C6H4CN
p-Me-C6H4CONHtBu
2
88
(CH3)3COH
p-Me-C6H4CN
p-Me-C6H4CONHtBu
2.30
85
(CH3)3COAc
m-Me-C6H4CN
m-Me-C6H4CONHtBu
2
94
(CH3)3COH
m-Me-C6H4CN
m-Me-C6H4CONHtBu
2
92
(CH3)3COAc
p-HO-C6H4CN
p-HO-C6H4CONHtBu
4
76
(CH3)3COH
p-HO-C6H4CN
p-HO-C6H4CONHtBu
4
70
(CH3)3COAc
p-NC-C6H4-CN
p-tBuNHOC-C6H4CONHtBu
4.30
92c
(CH3)3COH
p-NC-C6H4-CN
p-tBuNHOC-C6H4CONHtBu
5
90c
(CH3)3COAc
m-NC-C6H4-CN
m-tBuNHOC-C6H4CONHtBu
4.30
88c
(CH3)3COH
m-NC-C6H4-CN
m-tBuNHOC-C6H4CONHtBu
5
86c
(CH3)3COAc
CH2=CHCN
CH2=CHCONHtBu
3
66
(CH3)3COH
CH2=CHCN
CH2=CHCONHtBu
4
60
(CH3)3COAc
ClCH2CN
ClCH2CONHtBu
3.5
45
(CH3)3COH
ClCH2CN
ClCH2CONHtBu
4
42
(CH3)3COAc
NCCH2COOEt
tBuNHCOCH2COOEt
3.5
54
(CH3)3COH
NCCH2COOEt
tBuNHCOCH2COOEt
4
48
(CH3)3COAc
CH3CN
CH3CONHtBu
8
48
(CH3)3COH
CH3CN
CH3CONHtBu
9
45
All entries were carried on nitrile (5 mmol), oxalic acid dehydrate (2.5 mmol) and t-BuOAc or t-BuOH (5 mmol) at 70°C. bAll yields refer to isolated products. cNitrile (2.5 mmol) is used.