C

xc6h4nh2, (X)

Catalyst

T(°C)

t (min)

Cat : Substrate"

ArNHMe (Yield, %)

Selectivity, % (Mono/di)fc

NaY

130

195

1.2

84

98

h

K2C03

180

220

1.8

13

87c

-

150

200

-

2

100

p-no2

KY

150

600

3.3

79

93

p-CN

KY

150

270

3.3

83

98

o-C02Me

NaY

150

330

3.3

84

96

2,6(Me)2

NaY

150

300

3.3

76

94

aWeight quotient between the catalyst and the amine.

^The % selectivity is calculated with the expression {[ArNHMe]/([ArNHMe] + [ArNMe2])} x 100. cThirty-four percent of PhN(Me)C02Me was a by-product.

aWeight quotient between the catalyst and the amine.

^The % selectivity is calculated with the expression {[ArNHMe]/([ArNHMe] + [ArNMe2])} x 100. cThirty-four percent of PhN(Me)C02Me was a by-product.

Scheme 4.8 Mono-N-methylation of aromatic amines.

the presence of sodium-exchanged Y-zeolite (NaY faujasite) as a catalyst, the reaction of DMC with ambident nucleophiles such as aminophenols, -benzylalcohols, -benzoic acids, and -benzamides not only shows a very high mono-N-methyl selectivity (up to 99%), but it proceeds with complete chemoselectivity toward the amino group (Scheme 4.9).24

+ ch3oco2ch3

Me nh

Substrate

(%)

la: X = p-OH

90

100

91

lb: X = o-OH

90

100

97

2a:X=p-CH2OH

90

90

77

2b: X = o-CHOH2

90

99

92

3a: X = p-C02H

130

100

74

3b: X = o-C02H

150

95

83

4a: X = p-CONH2

90

96

86

4b: X = o-CONH2

90

100

91

Scheme 4.9 The selective methylation of ambident aromatic amines.

Scheme 4.9 The selective methylation of ambident aromatic amines.

The other nucleophilic functionalities (OH, CO2H, CH2OH, CONH2) are fully preserved from alkylation and/or transesterification reactions. In summary, all the nucleophiles indicated up to now are efficiently methylated (and monomethylated, where applicable) with DMC, both under CF and batch conditions.

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