Indium trichloride InCl

Catalysts such as Fe(BuEtCHC02)3 have been d eloped that are effective for the heteroatom Diels-Alder reaction. Indium trichloride (InCls) is a good catalyst for imino-Diels-Alder reactions. Hetero-Diels-Alder reactions involving carbonyls have been done in water. Ultrasound has been used to promote the Diels-Alder reactions of 1-azadienes. ... 

Loh, T.R, Pei, J., and Lin, M. (1996) Indium trichloride (InCl 3) catalysed Diels-Alder reaction in water. Chem. Comm. 2315-2316. 

T.-P. Loh, J. Pei, M. Lin, Indium Trichloride (InCl l) Catalyzed Diels-Alder Readion in Water Chem. Commun. 1996,2315-2316. 

However, in the presence of excess chlorine, indium trichloride, InCls is formed ... 

Indium trichloride (InCls) inhaled by female Fischer 344 rats initiated an inflammatory response (Blazka et al. 1994). Seven days foUowing inhalation of 20 mg InCh/m for 1 h the total cell number, fibronectin, and TNF-a levels in the bronchoalveo-lar lavage fluid were 8, 40, and 5 times higher than the control, respectively. While the increase was due primarily to an influx of polymorphonuclear leucocytes, a portion could be attributed to alveolar macrophages, which increased from 10.4 to 24.0 x 10 . 

Halides. Indium trichloride [10025-83-8] InCl, can be made by heating indium in excess chlorine or by chlorinating lower chlorides. It is a white crystalline soHd, deUquescent, soluble in water, and has a high vapor pressure. InCl forms chloroindates, double salts with chlorides of alkaLi metals, and organic bases. 

It was first reported in 1996 that indium trichloride catalyzes the Diels-Alder reaction in water [131]. The reaction of acrolein with cyclopentadiene in the presence of 20 mol% InCl proceeds stereoselectively (endo. exo=91 9) (Scheme 8.101). Without catalyst the reaction only goes to 60% completion (endo exo=74 26). The InCh-catalyzed Diels-Alder reaction works with either cyclic or non-cyclic dienes. InCh can be recovered for reuse after the reaction is completed. Indium triflate is also an effective catalyst for intramolecular Diels-Alder reactions of furans under microwave irradiation (Scheme 8.102) [132]. 

Indium trichloride and indium triflate are good catalysts also for the imino Diels-Alder reactions. With 20 mol% InClj, N-benzylideneaniline reacts with cyclopentadiene to give the corresponding tetrahydroquinoline derivative (Scheme 8.104) [134]. Similar InCls-catalyzed imino Diels-Alder reachons proceed with 3,4-dihy-dro-2H-pyrane, indene [135], and cychc enamides [136]. In contrast, cyclohexen-2-one gives no phenanthridinone, but azabicyclo [2.2.2]octanone is isolated (Scheme 8.105) [137]. The reachon seems to proceed through the formahon of die-nolate ion by strong coordinahon of InCb with the enone. 

When D-glucal is treated with 10 mol% InCl, 3H2O in acetonitrile the chiral furan diol is obtained. n-Galactal also undergoes transformation to the same product (Scheme 8.129) [172]. Indium tribromide and trichloride efficiently catalyze the chemoselective fhioacetalization of carbonyl compounds (Scheme 8.130) [173]. 

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