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Synthesis of Chiral Bicyclic Bis‐lactam Components for the controlled self‐assembly of hydrogen‐bonded arrays
Author(s) -
Brienne MarieJosèPhe,
Gabard Jacqueline,
Leclercq Martine,
Lehn JeanMarie,
Chevé Michel
Publication year - 1997
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19970800320
Subject(s) - chemistry , ceric ammonium nitrate , glyoxylic acid , bicyclic molecule , stereochemistry , ether , intramolecular force , ring (chemistry) , lactam , adduct , diol , medicinal chemistry , organic chemistry , grafting , polymer
The chiral biyclic bis‐lactams of structures 3 and 4 were synthesized from the key intermediate 2′b , the N,N′‐bis(4‐methoxybenzyl) derivative of 2 (X = MeO) ( Scheme 6 ). The synthesis of this intermediate involved two key steps: (1) a double condensation of glyoxylic acid/anisamide (= oxoacetic acid/4‐methoxybenzamide) adduct 11c with veratrole (1,2‐dimethoxybenzene; 10 ) allowed the introduction of two glycine units at the 4,5‐positions of the veratrole ring to give 18c ( Schemes 3 and 4 ); (2) in order to circumvent the hydrolysis of 4‐methoxybenzoyl protective groups which proved to be unfeasible, these groups were transformed into 4‐methoxybenzyl groups through a sequence involving thiocarbonylation followed by reduction ( Scheme 5 ). Thereafter, the double intramolecular cyclization of the resulting diamino diester 22c proceeded easily to afford 2′b. This intermediate may be transformed via the tetrol 2′g or the diol 2′h into the N ‐protected derivatives of 2 (X = OR) and of 3 (X = OCOR). Cleavage of the 4‐alkuxybenzyl groups was achieved by ceric ammonium nitrate. However, when the aromatic ring bore ether functions ( N ‐protected 2 ), this normal reaction was accompanied by the oxidative ring cleavage to give the diene‐diester structure 4 ( Schemes 5 and 6).