substitutions of the benzotriazolyl group in 3.5. [02JOC3109] Previous syntheses of 1,4-

dihydro-3(2H)-isoquinolinones, [93JHC381] tetrahydro[1,3]oxazolo[3,4-b]isoquinolin-3-

ones [99TA255] and tetrahydroisoquinolines [01TA2427] by intramolecular cyclizations

utilizing Lewis acid-activated benzotriazole as a leaving group, suggested a route to 3.1

by iminium cation Lewis acid promoted cyclizations of intermediates 3.5 (Scheme 3-1).

Success of the methodology led to its extension to prepare 2,3,10,10a-tetrahydro-

imidazo[1,5-b]isoquinolin- 1 (5H)-ones 3.2.

 0 R2 0

 N-R N-R1 I N-R1
 Ni/ N N
 R2 R3 O
 3.1 3.2 3.3


 Ph BtH Ph Ph-
 2 HCHO Nu-
 H-N NR N NR N N'R
 H H Bt Nu
 3.4 3.5 3.6

 L.A. -Bt

 -H+
 BtH = benzotriazole 3[ 1 -~ 3.1
 5N+ NR

 X

Scheme 3-1. Intramolecular cyclizations utilizing Lewis acid-activated benzotriazole

 3.2 Results and Discussion

3.2.1 Preparation of Chiral Diamines 3.11a-c from N-Boc-Phe-OH (3.7).

 N-Boc-a-amino-amides 3.9a-c were readily obtained from optically active N-Boc-

Phe-OH (3.7) and primary amines 3.8a-c (R =p-CH3C6H4, c-C6H11 or PhCH2) using the

mixed anhydride method. [01JCS(P1)1767] [00TL37] We previously used excess