Preparation, Crystal Structures, and Properties of New Conjugated π-Electron Systems with 3-Guaiazulenyl and 4-(Dimethylamino)phenyl Groups

Abstract

Reaction of guaiazulene with 1,2-bis[4-(dimethylamino)phenyl]-1,2-ethanediol in methanol in the presence of hydrochloric acid at 60 °C for 3 h gives 1,1-bis[4-(dimethylamino)phenyl]-2-(3-guaiazulenyl)ethylene, in 81% yield, via pinacol rearrangement and further Wittig reaction of 3-formylguaiazulene with [4-(dimethylamino)benzyl]triphenylphosphonium bromide in ethanol containing NaOEt at 25 °C for 24 h under argon affords (E)-2-[4-(dimethylamino)phenyl]-1-(3-guaiazulenyl)ethylene in 12% yield. Crystal structures as well as spectroscopic and electrochemical properties of the products, with a view to comparative study, are reported. Moreover, reactions of the products with 2 equiv of tetracyanoethylene (TCNE) in benzene at 25 °C for 24 h under argon give 1,1,2,2,11,11,12,12-octacyano-3,3-bis[4-(dimethylamino)phenyl]-8-isopropyl-5,10-dimethyl-1,2,3,6,9,10a-hexahydro-6,9-ethanobenz[a]azulene and 1,1,2,2,11,11,12,12-octacyano-3-[4-(dimethylamino)phenyl]-8-isopropyl-5,10-dimethyl-1,2,3,6,9,10a-hexahydro-6,9-ethanobenz[a]azulene in 74 and 41% yields. A plausible reaction pathway for the formation of the unique products, possessing interesting structures, is submitted.

A Visit to Wittig and Arsa-Wittig Reactions

“…Despite the lower electrophilic character of the carbonyl group in position 1 of azulenes than that of other aromatic aldehydes, good yields were obtained for the condensation products starting from alkylated azulenes. The 4-dimethylamino substituent drops the yield [12] to 12 % whereas the nitro group increases the yield until 92 % [1] similar to the yields obtained for the unsubstituted phenyl. The reaction produced E isomer of alkene or a mixture of E/Z isomers depending the starting materials.…”

An Efficient Preparation, Spectroscopic Properties, and Crystal Structure of 1,1-Bis(4-[2-(dimethylamino)ethoxy]phenyl)-2-(3-guaiazulenyl)ethylene

“…Similarly, the reaction of guaiazulene with 1,2-bis(4-hydroxyphenyl)-1,2-ethanediol under the same reaction conditions as the above afforded 2-(3-guaiazulenyl)-1,1-bis(4-hydroxyphenyl)ethylene (3) (see Figure 3) in 73% yield [7]. As a series of basic studies on our azulene chemistry [7][8][9][10][11][12][13][14][15][16][17], our interest has quite recently been focused on an efficient preparation and properties of new tamoxifen analogues with a 3-guaiazulenyl (7-isopropyl-1,4-dimethylazulen-3-yl) group, for example, the title compound 4. We now wish to report a facile preparation as well as the spectroscopic properties and the crystal structure of the target compound 4 (see Figure 3).…”

Synthesis of azulenic compounds with a homo- or hetero-atomic double bond at position 1

“…24,75 As it is illustrated for guaiazulene in Scheme 26, the reaction leads to the product of pinacol rearrangement, 82. While good yields are obtained for guaiazulene and 1-chloroazulene, azulene reacts in lower yield and methyl azulene-1-carboxylate gives no product.…”