Efficient Synthesis of Substituted Indene Derivatives

Abstract

General procedure for the synthesis of 1-acetoxy-1H-indene-2-carboxylic acid alkyl ester 2a-eTo a mixture of alcohol 1 (5 mmoles), acetic anhydride (25 mmoles) in 40 mL of anhydrous ether cooled at 0 °C under stirring in nitrogen atmosphere, was added a drop of concentrated sulfuric acid. After completion of the reaction, the mixture was hydrolyzed with ice water and extracted with ether (3x20 mL). The organic layers were washed successively with sodium hydroxide solution (1.5M) and brine until neutral pH then dried over MgSO 4 and concentrated in vacuo. After evaporating of the solvent, The residue obtained was purified by silica gel column chromatography (AcOEt:Hexane, 7/3). The spectral ( 1 H and 13 C NMR and HRMS) data of the unknown compounds 2a-e are given below.Selected Data 1-Acetoxy-1H-indene-2-carboxylic acid methyl ester 2a

Recent Advances in the Synthesis of Indanes and Indenes

“…Synthesis of 1-alkylated indene-2-carboxylates 390 by reaction between 1-acetoxy-1H-indene-2-carboxylate 389 and Grignard reagents in the presence of catalyticamountso fLiCuBr 2 . [144] Scheme151. Synthesis of functionalizedi ndenes 392 by thermal isomerization of iminolactones 391.…”

“…[143] Indenyl acetates can be used as suitable allylic substrates for the b-alkylation reactionw itho rganocopper reagents.T hus, the reaction of ethyl 1-acetoxy-1H-indene-2-carboxylate 389 with the organocopper intermediates generated in situ from Grignardr eagents and ac atalytic amount of LiCuBr 2 led to the formation of 1-alkylated indene-2-carboxylates 390 in good yields, as shown in Scheme150. [144] Another interesting transformation was published recently.I t consisted of the thermali somerization of iminolactones 391 (obtained by the reaction between alkyl isocyanides, carbonyl compounds, and acetylenic diesters) into functionalized indenes 392,c arriedo ut in refluxing p-xylene (Scheme 151). [145] A ring opening-ring closurem echanism was proposedf or this process (Scheme 151).…”

“…Indenyl acetates can be used as suitable allylic substrates for the β‐alkylation reaction with organocopper reagents. Thus, the reaction of ethyl 1‐acetoxy‐1 H ‐indene‐2‐carboxylate 389 with the organocopper intermediates generated in situ from Grignard reagents and a catalytic amount of LiCuBr 2 led to the formation of 1‐alkylated indene‐2‐carboxylates 390 in good yields, as shown in Scheme …”

“… Synthesis of 1‐alkylated indene‐2‐carboxylates 390 by reaction between 1‐acetoxy‐1 H ‐indene‐2‐carboxylate 389 and Grignard reagents in the presence of catalytic amounts of LiCuBr 2 …”

New substituted indene derivatives from bicyclic Baylis-Hillman acetate

“…They were used as templates for the synthesis of various alkyl 1-acetoxy-1H-indene-2-carboxylates 2a-e and various functionalized-1H-indene esters 3 through SN2'-type addition-elimination reaction 42 as shown in Scheme 2.…”