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Über Umlagerungen bei der Cyclialkylierung von Arylpentanolen zu 2,3‐Dihydro‐1 H‐ inden‐Derivaten, 1. Mitteilung
Author(s) -
Blum Roger,
Giovannini Edgardo,
Hengartner Urs,
Vallat Gabriel
Publication year - 2002
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 - 10.1002/1522-2675(200206)85:6<1827::aid-hlca1827>3.0.co;2-j
Subject(s) - chemistry , indene , medicinal chemistry , substituent , stereochemistry
On Rearrangements by Cyclialkylations of Arylpentanols to 2,3‐Dihydro‐1 H ‐indene Derivatives. Part 1. An Unexpected Rearrangement by the Acid‐Catalyzed Cyclialkylation of 4‐(2‐Chlorophenyl)‐2,4‐dimethyl pentan‐2‐ol under Formation of trans ‐4‐Chloro‐2,3‐dihydro‐1,1,2,3‐tetramethyl‐1 H ‐indene The acid‐catalyzed cyclialkylation of 2,4‐dimethyl‐4‐phenylpentan‐2‐ol led exclusively to the expected product, 2,3‐dihydro‐1,1,3,3‐tetramethyl‐1 H ‐indene. However, analogous cyclialkylation of 4‐(2‐chlorophenyl)‐2,4‐dimethylpentan‐2‐ol ( 1 ) gave a ca. 1 : 1 mixture of 4‐chloro‐2,3‐dihydro‐1,1,3,3‐tetramethyl‐1 H ‐indene ( 2 ) and of trans ‐4‐chloro‐2,3‐dihydro‐1,1,2,3‐tetramethyl‐1 H ‐indene ( 3 ; Scheme 1 ). The specific action of the Cl substituent is investigated and a mechanism for this unexpected frame‐work transposition proposed.