Methods of Non-a-Amino Acid Synthesis, 2nd Edition

190

Methods of Non-α-Amino Acid Synthesis, Second Edition

The reaction of 112 with phenethylamine gave a protected aminocyclopentane

derivative. Both 112a and 112b were converted to the corresponding amine (113a

or 113b). Deprotection by catalytic hydrogenation led to 114a [ethyl 2-(2-amino-1-

cyclopentyl)ethanoate; 4% overall yield] or 114b [ethyl 2-(2-amino-1-cyclopentyl)

propanoate; 38% overall yield].

84

O

(CH

2

)

n

CO

2

Et

N

(CH

2

)

n

CO

2

Et

NH

2

(CH

2

)

n

CO

2

Et

H

Ph

Me

H

2

N

Me

Ph

1.

2. H

2

, Ni (R)

1. H

2

, Pd-C

2. HCl

112 11

31

14

(a) n = 1 (b) n = 2

A different approach used keto-ester 115

85

to form an enamine, which reacted

with 4-methoxybenzyl bromide to give 116

86

using the Stork ...