Photochromism of diarylethene derivatives having an indene unit

Photochromic indene derivatives, 1-(2-methyl-1-inden-3-yl)-2-(2-methyl-1-benzothien-3-yl)perfluorocyclopentene and 1-(2-methyl-1-inden-3-yl)-2-(2-methyl-1-benzofuran-3-yl)perfluorocyclopentene, were synthesized and their photochromic performance was examined.     

Selective alkylation and Suzuki coupling as an efficient strategy for introducing functional anchors to the ethylene-bis(indenyl) ligand

Chiral ansa-ethylene-bis(indenyl)-metal complexes, EBI-MX₂, are useful pre-catalysts for a wide variety of reactions, including hydrogenations, hydrosilylations, and polymerization reactions. In order to immobilize these complexes onto heterogeneous supports, a new methodology was developed to introduce functional anchors to the ethylene-bis(indenyl) ligand, EBI. This was accomplished by selective alkylation of indene to form toluene-4-sulfonic acid 2-(3H-inden-1-yl)-ethyl ester, which was then used to alkylate 6-bromoindene. The selective introduction of an aryl bromide then undergoes coupling reactions with aryl borates via the Suzuki coupling to efficiently introduce an alkenyl or alcohol, functional anchor in a simple four step synthesis.     

多环麝香的分子结构和香气之间的关系

本文综述了多环麝香的当前进展,并提出了系统的分类方法。对各种多环麝香(茚满型,萘满型,异色满型,氢化引达省型,苊型)香味与分子结构之间关系的研究进行了总结,还作了比较。并描述了多环分子中环上取代基的性质,数量和位置对麝香香味的影响。     

Synthesis of indenes by ytterbium-catalyzed carboalkoxylation/Friedel-Crafts reaction of arylidenecyclopropanes with acetals

Ytterbium-catalyzed tandem carboalkoxylation/Friedel-Crafts reaction of arylidenecyclopropanes 1 with acetals 2 afforded the corresponding indene derivatives 3 in good to high yields. For example, in the presence of 10 mol % of Yb(OTf)₃ the reaction of 1-phenylbenzylidenecyclopropane 1a with the dimethyl acetals of benzaldehyde 2a, p-tolualdehyde 2b, and p-anisaldehyde 2c gave 1,3-diphenyl-2-(2-methoxyethyl)indene 3a, 2-(2-methoxyethyl)-3-phenyl-1-(p-tolyl)indene 3b, and 1-(p-anisyl)-2-(2-methoxyethyl)-3-phenylindene 3c in 82%, 80%, and 80% yields, respectively.     

Synthesis of 2-bromo-1-aryl-1H-indenes via a Ag(I) promoted domino 2π-electrocyclic ring-opening/4π-electrocyclization reaction of 1,2-diaryl substituted gem-dibromocyclopropanes

2-Bromo-1-aryl substituted indenes can be synthesized from 1,2-diaryl substituted gem-dibromocyclopropanes via a domino reaction sequence. The cascade reaction involves silver(I) promoted ionization and 2π-disrotatory electrocyclic ring-opening, followed by a 4π-conrotatory electrocyclic ring closing reaction of the allylic carbocation intermediate. Reaction conditions utilize silver tetrafluoroborate (AgBF₄) in dichloroethane at 65 °C. Selectivity effects for the electrocyclization were also studied. The 2-bromoindenes can be further functionalized using cross-coupling reactions, such as the Suzuki–Miyaura protocol. The alkene π-bond of the indenes can also be isomerized to give the thermodynamically more stable 2-bromo-3-aryl-1H-indene isomers using triethylamine in dichloromethane at room temperature.     

Au-catalyzed isomerization of cyclopropenes: a novel approach to indene derivatives

AuPPh₃Cl/AgOTf-catalyzed reaction of cyclopropenes is found to be highly efficient, giving indene derivatives in high yields. The reaction is suggested to proceed through gold vinyl carbenoid intermediate.     

Preparation of chiral indenes containing β-pinenyl derived ligand substituents

A simple procedure for the preparation of new 1-, 2- and 1,3-chirally substituted indenes is described in which indenyllithium or 2-indenylmagnesium bromide is reacted with a β-pinenyl derived chlorosilane. Synthesis of the ethylene bridged bis(indene) analogues of two of the new compounds is also described.     

Studies towards the synthesis of FCRR toxin: an expeditious entry into 7-5-6 ring systems via [5+2] oxidopyrylium-alkene cycloaddition

Synthetic studies towards the diterpene natural product FCRR toxin have been undertaken. An intermolecular [5+2] oxidopyrylium-alkene cycloaddition reaction was employed to construct the 7-5-6 tricyclic framework. The reaction proceeded with very high regio- and stereoselectivity and the bridging ether was reductively cleaved to unmask the carbocycle.     

Synthesis of indenothiophenone derivatives by cycloaromatization of non-conjugated thienyl tetraynes

Non-conjugated thienyl tetrayne derivatives 1-3 are prepared as novel building block for the construction of indenothiophenone derivatives. Oxidation of 1-3, followed by cycloaromatization of the corresponding ketone derivatives 13-15 proceeds smoothly to afford indenothiophenone derivatives 16-21 in good yields.