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Conformational study by CD of chirally tethered naphthalene moieties: Toward an understanding of the asymmetric intramolecular coupling reaction?
Author(s) -
Rosini Carlo,
Superchi Stefano,
Bianco Giuliana,
Mecca Tommaso
Publication year - 2000
Publication title -
chirality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.43
H-Index - 77
eISSN - 1520-636X
pISSN - 0899-0042
DOI - 10.1002/(sici)1520-636x(2000)12:4<256::aid-chir11>3.0.co;2-4
Subject(s) - chemistry , intramolecular force , chirality (physics) , naphthalene , stereoselectivity , stereochemistry , asymmetric induction , derivative (finance) , coupling reaction , enantioselective synthesis , catalysis , organic chemistry , financial economics , economics , chiral symmetry breaking , physics , quantum mechanics , nambu–jona lasinio model , quark
The carbonate (R,R)‐ 1 and the diester (R,R)‐ 2, precursors of optically active 1,1′‐binaphthyl derivatives through asymmetric intramolecular coupling, were prepared and fully characterized. The absorption and CD spectra, together with the cholesteric induction measurement of (R,R)‐ 1, indicate that it assumes a conformation in which the naphthalene rings are M‐skewed. Since the intramolecular coupling of (R,R)‐ 1 affords a P‐twisted (S) binaphthyl derivative, a change of twist from M to P must occur during the reaction. Moreover, this conformation allows the coupling to occur along only one pathway, thus explaining the high stereoselectivity. The CD analysis of (R,R)‐ 2 indicates that it assumes a rigid conformation as well, with the naphthalene rings fixed relative to each other. However, in this compound the naphthalene moieties can give rise to a coupling reaction following two different pathways, leading to oppositely configured binaphthyls with almost the same probability so that low stereoselectivity results. Chirality 12:256–262, 2000. © 2000 Wiley‐Liss, Inc.