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Synthesis, Stability, and Crystal Structure of an Azulenium Cation Containing an Adamantyl Group
Author(s) -
Oda Mitsunori,
Nakajima Nobue,
Thanh Nguyen Chung,
Kitahara Kazuhiro,
Miyatake Ryuta,
Kuroda Shigeyasu
Publication year - 2008
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.200800700
Subject(s) - chemistry , aldol reaction , adduct , hydride , trimethylsilyl , cycloheptatriene , crystal structure , stereochemistry , medicinal chemistry , crystallography , organic chemistry , catalysis , hydrogen
Abstract Starting from the trimethylsilyl enol ether of 1‐acetyl‐1,3,5‐cycloheptatriene, the title 1 H ‐azulenium cation was synthesized by a five‐step sequence that involved a Noyori–Mukaiyama aldol reaction, a Nazarov cyclization, a Shapiro reaction, and a hydride abstraction. The Nazarov reaction of the aldol‐type adduct resulted in the formation of an unusual double‐bond position isomer, which has never been obtained in similar reactions forming tetrahydroazulenones. The p K R + value of the title cation was found to be 9.8, which is less than that expected by inductive stabilization from the number of carbons at the 1‐position. The X‐ray crystal structure of the title cation (ClO 4 – salt) reveals CH–O interactions and deformation of the azulenyl ion part.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)