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Metal‐Catalyzed Cyclization of β‐ and γ‐Allenols Derived from D ‐Glyceraldehyde—Synthesis of Enantiopure Dihydropyrans and Tetrahydrooxepines: An Experimental and Theoretical Study
Author(s) -
Alcaide Benito,
Almendros Pedro,
del Campo Teresa Martínez,
Soriano Elena,
MarcoContelles José L.
Publication year - 2009
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200901180
Subject(s) - enantiopure drug , regioselectivity , chemistry , catalysis , palladium , metal , combinatorial chemistry , bromide , stereochemistry , organic chemistry , enantioselective synthesis
Regiocontrolled metal‐catalyzed preparations of enantiopure dihydropyrans and tetrahydrooxepines have been synthesized starting from β‐ and γ‐allenols derived from D ‐glyceraldehyde. The Pd II ‐catalyzed cyclizative coupling reactions of β‐allenols 1 a and 1 b with allyl bromide effectively afforded enantiopure tetrafunctionalized dihydropyrans through a 6‐ endo oxycyclization protocol, whereas the gold‐, platinum‐, and palladium‐mediated heterocyclization of γ‐allenol 2 furnished tetrahydrooxepines 13 – 16 through regioselective 7‐ endo‐ trig oxycyclization reactions. Moreover, density functional calculations were performed to predict the regioselectivity of the γ‐allenol cycloetherification to tetrahydrooxepines on the basis of both the tether nature and characteristics of the metals, and to gain an insight into the mechanism of the oxycyclization reactions.