The synthesis of the new chiral ligands 6ae, 8ae. 9ae, and 11ae starting from the chiral beta-[(Boc)-amino]sulfonamide 3ae is reported. The beta-amino group of 3ae was deprotected and condensed with 3,5-dichlorosalicylaldehyde (4) to yield the known Schiff base 5ae, which was then reduced to the amino compound 6ae (Scheme 3). Alternatively, condensation of the free amino compound with 2-(diphenylphosphanyl)benzaldehyde (7) afforded the imino ligand 8ae which upon reduction yielded the amino ligand 9ae (Scheme 4). The free amino compound derived from 3ae was also coupled with 2-(diphenylphosphanyl)benzoic acid (10) to give ligand 11ae (Scheme 5). These ligands were tested in the copper-catalysed allylic substitution reaction of cinnamyl (= 3-phenylprop-2-cnyl) phosphate 12 with diethylzinc as a nucleophile. Ligands 5ae. 6ae, 8ae. and 11ae gave excellent ratios (100:0) of the S(N)2'/S(N)2 products (Scheme 6 and Table 1). Ligand 11ce, identified from the screening of a small library of ligands of general formula 11, promoted the allylic substitution reaction with moderate enantioselectivity (40% for the S(N)2' product 13 (Scheme 8 and Table 3)).

Synthesis and screening of new chiral ligands for the copper-catalysed enantioselective allylic substitution / S. Ongeri, U. Piarulli, M. Roux, C. Monti, C.M.A. Gennari. - In: HELVETICA CHIMICA ACTA. - ISSN 0018-019X. - 85:10(2002), pp. 3388-3399. [10.1002/1522-2675(200210)85:10<3388::AID-HLCA3388>3.0.CO;2-I]

Synthesis and screening of new chiral ligands for the copper-catalysed enantioselective allylic substitution

C. Monti
Penultimo
;
C.M.A. Gennari
Ultimo
2002

Abstract

The synthesis of the new chiral ligands 6ae, 8ae. 9ae, and 11ae starting from the chiral beta-[(Boc)-amino]sulfonamide 3ae is reported. The beta-amino group of 3ae was deprotected and condensed with 3,5-dichlorosalicylaldehyde (4) to yield the known Schiff base 5ae, which was then reduced to the amino compound 6ae (Scheme 3). Alternatively, condensation of the free amino compound with 2-(diphenylphosphanyl)benzaldehyde (7) afforded the imino ligand 8ae which upon reduction yielded the amino ligand 9ae (Scheme 4). The free amino compound derived from 3ae was also coupled with 2-(diphenylphosphanyl)benzoic acid (10) to give ligand 11ae (Scheme 5). These ligands were tested in the copper-catalysed allylic substitution reaction of cinnamyl (= 3-phenylprop-2-cnyl) phosphate 12 with diethylzinc as a nucleophile. Ligands 5ae. 6ae, 8ae. and 11ae gave excellent ratios (100:0) of the S(N)2'/S(N)2 products (Scheme 6 and Table 1). Ligand 11ce, identified from the screening of a small library of ligands of general formula 11, promoted the allylic substitution reaction with moderate enantioselectivity (40% for the S(N)2' product 13 (Scheme 8 and Table 3)).
Settore CHIM/06 - Chimica Organica
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/175257
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