General Papers ARKIVOC 2012 (vi)

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1 Geeral Papers AKIVC 2012 (vi) Five- ad six membered cyclic α-acylviyl aioic sythos: Sythesis of α-trimethylsilyl-α,β-usaturated cycloalkeoes ad their coversio ito 2-(hydroxydimethylsilyl)cycloalk-2-eoes through carbo silico bod scissio 1 Divya Jyothi ad HariPrasad Suresh* Departmet of Post-Graduate Studies i Chemistry, Cetral College Campus, Bagalore Uiversity, Bagalore , Idia hariprasad@bub.eret.i Dedicated to Prof. G. Nagedrappa, etired Professor of rgaic Chemistry, Bagalore Uiversity, Bagalore, Idia, o his 70 th birthday Abstract Five- ad six-membered α-trimethylsilyl-α,β-usaturated cycloalkeoes were prepared by the Wurtz-Fittig couplig reactio of the correspodig 6-bromo-1,4-dioxaspiro[4,]cycloalk-6-ees with sodium ad chlorotrimethylsilae. Upo treatmet with ahydrous Al 3, the compouds uderwet carbo-silico bod scissio to yield a ovel class of compouds: the 2- (hydroxydimethylsilyl)cycloalk-2-eoes. Keywords: α-trimethylsilyl-α,β-usaturated cycloalkeoes, Wurtz-Fittig reactio, Lewis acid, 2-(hydroxydimethylsilyl)cycloalk-2-eoes, carbo-silico bod scissio Itroductio α-trimethylsilyl-α,β-usaturated cycloalkeoes form a importat class of compouds i sythetic orgaic chemistry. The compouds are cyclic α-acylviyl aioic sythos. 2 There are oly a few reports for preparatio of cyclic α- or β-acylviyl aioic sythos. The sythos bearig either the silyl- or the stayl- 3 group act as a maskig aget for the aios. The most commo route reported i literature for the preparatio of α-trimethylsilyl-α,β-usaturated cycloalkeoes is the reactio of -butyl lithium with the correspodig 6-halo-1,4- dioxaspiro[4,]cycloalk-6-ees at -78 ºC, followed by quechig of the resultig aio with chlorotrimethylsilae. Subsequet workup yields α-trimethylsilyl-α,β-usaturated cycloalkeoe. 4-8 Page 194

2 Geeral Papers AKIVC 2012 (vi) We had earlier reported the preparatio of a wide variety of simple ad substituted cyclic viyl silaes, by the simple Wurtz Fittig couplig reactio of the correspodig halocycloalkee with sodium ad chlorotrimethylsilae i differet ahydrous solvets I this article we report the sythesis of some α-trimethylsilyl-α,β-usaturated cycloalkeoes employig the Wurtz Fittig couplig reactio, ad their coversio to ovel 2- (hydroxydimethylsilyl)cycloalk-2-eoes through carbo silico bod scissio. esults ad Discussio I cotiuatio of our studies for the preparatio of some ovel cyclic viyl silaes, ad further expasio of the Wurtz Fittig couplig reactio, we explored the preparatio of some silylsubstituted cyclic α,β-usaturated eoes. The compouds are cyclic α-acylviyl aioic sythos with trimethylsilyl-group behavig as a maskig aget. I this study, we report the successful sythesis of the five- ad six-membered 2- trimethylsilylcycloalkeoes 4a to 4d usig the Wurtz Fittig couplig reactios. α-bromo-α,β-usaturated cycloalkeoes 12 1a to 1d were coverted ito the correspodig 6-bromo-1,4-dioxaspiro[4,]alk-6-ees 2a to 2d by the azeotropic removal of water usig ethylee glycol, p-tsh/toluee. The acetals 2a to 2d upo Wurtz Fittig couplig reactio with sodium ad chlorotrimethylsilae i ahydrous ether solvet gave the correspodig 6- trimethylsilyl-1,4-dioxaspiro[4,]alk-6-ees 3a to 3d, whe followed by GC. The 6- trimethylsilyl-1,4-dioxaspiro[4,]alk-6-ees however were foud to be highly ustable eve to the mildest acidic medium. The 2-trimethylsilylcycloalkeoes 4a to 4d were formed through H acid catalyzed cleavage ad removal of the ethylee glycol (Scheme 1). Br (CH 2 H) 2, PTSA, Br Na, Me 3 Si SiMe 3 work-up SiMe 3 toluee Ether, C - rt 1a: =1, =H 1b: =1, = 1c: =2, =H 1d: =2, = 2a: =1, =H 2b: =1, = 2c: =2, =H 2d: =2, = 3a: =1, =H 3b: =1, = 3c: =2, =H 3d: =2, = 4a: =1, =H 4b: =1, = 4c: =2, =H 4d: =2, = Scheme 1. Sythesis of some 2-trimethylsilylcycloalkeoes. To the best of our kowledge, the oly other report of usig alkali metal for such reactios has bee reported by Yus, who used metallic lithium for the preparatio of 6-trimethylsilyl-1,4- Page 195

3 Geeral Papers AKIVC 2012 (vi) dioxaspiro[4,5]dec-6-ee (3c). However, he has reported that the treatmet of 3c with oxalic acid failed to produce 2-trimethylsilylcyclohexeoe 4c. 13 Therefore, our procedure which employs the Wurtz Fittig couplig reactio usig sodium ad chlorotrimethylsilae is a simple method for the preparatio of 2- trimethylsilylcycloalkeoes 4a to 4d. The coditios for the formatio of the compouds 4a to 4d have bee stadardized ad the optimized isolated yields reported. Coversio to ovel 2-(hydroxydimethylsilyl)cycloalk-2-eoes The compouds 4a to 4d were subjected to the Friedel Crafts acylatio reactio i a attempt to prepare some ovel cycloalkeyl-β-diketoes. 14 This reactio was expected to employ the β-silyl effect. 15 eactio of 2-trimethylsilylcycloalkeoes 3a to 3d with several acid chlorides ad ahydrous Al 3 i ahydrous dichloromethae solvet i the ratio 1:3:3 16a did ot yield the expected cycloalkeyl-β-diketoes whe moitored by GC ad TLC. As a further alteratio from the stadard 1:3:3 reactio coditios as give by Flemig, 16b several experimets were coducted ad the reactio coditios modified. As a test cadidate 3- methyl-2-trimethylsilylcyclohexeoe (4d) was chose for further reactios. Some of the parameters that chaged with 4d were: (1) whe the molar equivalet quatity of Lewis acid was raised from three to five equivalets, the TLC showed oly trace amouts of disappearace of the startig material. Whe the cocetratio of Lewis acid was raised to seve molar equivalets, a ew spot was observed o TLC at f value ~ 0.3. The extet of coversio of the startig viylsilae was still oly 30% after half a hour. (2) However, with the use of te molar equivalets of the Lewis acid (ahydrous Al 3 ), the startig material disappeared completely withi 30 miutes givig a sigle spot o the TLC plate with f value ~ 0.3. The compoud was isolated after regular work-up ad was foud to be 2-(hydroxydimethylsilyl)-3-methylcyclohex- 2-eoe: (5d), formed by the carbo silico bod scissio i the trimethylsilyl-group (Scheme 2). H Si Lewis acid, Si CH 2 2, 0 0 C-rt, 30 mi 4a - 4d 5a - 5d = H or = 1,2 Scheme 2. Sythesis of some ovel 2-(hydroxydimethylsilyl)cycloalk-2-eoes. The formatio of the ovel cyclic ketoviylsilaol 5d was highly seredipitous. To our kowledge, there are o reports of such a reactio which yields such ovel cyclic Page 196

4 Geeral Papers AKIVC 2012 (vi) ketoviylsilaols. The ovel cyclic ketoviylsilaols form a ew class of reagets i orgaosilico chemistry. The formatio of cyclic ketoviylsilaols idicated the promiet role of the ahydrous Al 3 as Lewis acid i the reactio. To cofirm the above coclusio we carried out the reactio of 4d i the absece of bezoyl chloride ad isolated 5d i 96% isolated yield. This idicated that there was o role for the acid chlorides durig the progress of the reactio. Further reactios were carried out to study the efficacy of differet Lewis acids. The other Lewis acids chose for the study were Bi 3, S 4, Ti 4 ad Z 2. Te molar equivalets of the Lewis acid was take for each reactio, with oe molar equivalet of 4d. Durig these reactios, Bi 3 did ot produce ay yield. S 4 ad Ti 4 gave moderate yields i the rage of 40 45%, whereas Z 2 produced oly 20% coversio to ketosilaol after 12 hours of reactio time. This idicated that the ahydrous Al 3 was the best Lewis acid for formatio of the cyclic ketoviylsilaols uder the coditios we have employed. The reactio coditios were exteded to the compouds 4a-4c. We foud that with the use of ahydrous Al 3, the resultig product was a sigle compoud of high purity ad yield i all the cases. The products that were formed i approximately 30 miutes yielded greater tha 95%. The reactios were carried out for a miimum of three experimets i each case of 4a-4d, ad the results were cosistet. From the results obtaied we cocluded that these reactios are geeral for the formatio of the ovel cyclic ketoviylsilaols 5a to 5d. The compouds 5a to 5d are stable probably because of itramolecular hydroge bodig betwee the keto-group ad the hydroxyl-group of the silaol. Some work was carried out to determie the mechaism for the formatio of the ovel cyclic ketoviylsilaols 5a to 5d. We propose the mechaism for the formatio of the ovel cyclic ketoviylsilaols 5a-5d as show i Scheme 3. It is reasoed that the additio of ahydrous Al 3 first leads to the formatio of a tight complex with the oxyge of the keto-group. Due to the close proximity of chlorie ad silico, it is expected that the o-bodig electros of chlorie first form a petacoordiate itermediate with silico exhibitig dsp 2 hybridizatio. Upo additio of water, we expect the hybridizatio of the silico to chage from dsp 2 to dsp 3 ad formatio of a hexacoordiated itermediate. Such peta- ad hexa-coordiated silyl-compouds are well documeted i literature. 17,18 Subsequet quechig with excess water leads to the elimiatio of H, CH 4 ad Al(H) 3 to yield the ovel cyclic ketoviylsilaols 5a-5d. We have tried to isolate the petacoordiated complex by freeze-evaporatig the solvet. Vacuum strippig off the solvet resulted i a brow amorphous solid. The powder X-ray of sublimed ahydrous Al 3 shows a chage of profile compared to the complex, idicatig the complexatio of Al 3 with the ketoe. Ufortuately, we were uable to recrystallize the complex i crystallie form to obtai a sigle crystal X-ray. Page 197

5 Geeral Papers AKIVC 2012 (vi) Further, the brow amorphous complex was treated with water to idetify the evolutio of CH 4 gas. The evolutio of CH 4 gas too was ot observed, probably due to small scale (0.1 g) reactio. 4a - 4d Si Al 3 Al Si Al Si = 1,2 = H, H 2 H Si 5a - 5d + excess H 2 _ 3H CH 4 Al(H) 3 Al Si H 3 C H H Scheme 3. Proposed mechaism for the formatio of 2-(hydroxydimethylsilyl)cycloalk-2- eoes. The isolatio of the ovel ketoviylsilaols 5a-5d prompted us to do a literature survey. The oly reported istace for such a uusual carbo silico scissio has bee give by Dubois et al. 19 Trimethylsilylcycloalkaes upo reactio with oe equivalet of acetyl chloride ad oe equivalet of ahydrous Al 3 are reported to udergo C Si bod scissio to form chlorosilaes. Upo hydrolysis, the chlorosilaes form the correspodig silaols. The silaols beig ustable were reported to udergo codesatio to elimiate water to form the more stable disiloxaes. I our reactios, it was foud that the isolated ovel cyclic ketoviylsilaols 5a-5d are highly stable ad ca be stored by freezig for ay period of time. We reaso this to be due to itramolecular hydroge-bodig betwee the keto-group ad the silaol as idicated for 5a-5d i Scheme 3. Page 198

6 Geeral Papers AKIVC 2012 (vi) The drivig force for the formatio of the stable ovel cyclic ketoviylsilaols may be due to the bod stregths betwee silico ad various other elemets. A compariso of the dissociatio eergies betwee silico ad oxyge shows the stregth of the Si bod as 536 kj mol -1 ad for the Si bod as 472 kj mol This shows that silico has more affiity for bodig with oxyge, whe compared to chlorie. The formatio of a petacoordiated complex is due to the close proximity of chlorie with silico, i the presece of Al 3, as depicted i Scheme 3. However, durig work-up the chlorie is replaced by the hydroxyl-group of water through a fleetig hexacoordiated complex itermediate, to ultimately yield the stable keto-silaols 5a to 5d. Coclusios The sythesis of five- ad six-membered α-trimethylsilyl-α,β-usaturated cycloalkeoes by the Wurtz Fittig couplig reactio of the correspodig 6-halo-1,4-dioxaspiro[4,]cycloalk-6-ees with sodium ad chlorotrimethylsilae ad their coversio to a ew class of orgaosilyl-based reagets the 2-(hydroxydimethylsilyl)cycloalk-2-eoes is reported. Experimetal Sectio Geeral. All the reactios were performed i ove dry apparatus. eactios were moitored o Merck TLC plastic sheets of silica gel 60 F254 pre-coated plates, with elutio solvet 1: 4 mixture of ethyl acetate: hexae (60 80º C). GC was ru o SE-30 SS 2m 1/8 colum o Shimadzu 14-B / Mayura 9800 gas chromatographs. The yields refer to the optimum isolated products. Ifrared spectra were recorded usig a Nicolet 400D FT-I ad Perki-Elmer 1310 I spectrophotometer ad the frequecies are reported i wave umber (cm 1 ). NM spectra were recorded o 300 or 400 MHz AMX Bruker NM spectrophotometer ad the chemical shifts are relative to CH 3 for compouds with the trimethylsilyl-group, ad to tetramethylsilae for those without the trimethylsilyl-group. Multiplicity is idicated usig the followig abbreviatios: s (siglet), d (doublet), dd (double doublet), t (triplet), m (multiplet), bs (broad siglet) ad br (broad). H-MS spectra were recorded o a Q-TF electro-spray istrumet. Geeral procedure for preparatio of 6-bromo-1,4-dioxaspiro[4,]alk-6-ees A mixture cosistig of 30 mmol of α-bromo-α,β-usaturated carboyl compoud (1a-1d), 250 ml of bezee, 4.2 ml of ethylee glycol, ad 25 mg of p-tolueesulfoic acid were heated at reflux for azeotropic removal of water usig the Dea-Stark apparatus. The resultig mixture was cooled ad filtered through a filter cake cosistig of 5g of MgS 4 ad 5g of silica gel. The filter cake was washed with 150 ml of CH 2 C1 2. The filtrate ad washigs were combied ad cocetrated i-vacuo ad subjected to distillatio to obtai the pure product. Page 199

7 Geeral Papers AKIVC 2012 (vi) Bromo-l,4-dioxaspiro[4,4]o-6-ee (2a) 5. Colourless oil, bp: bath 60 ºC (1.5 mm); I (ν max, cm -1 ): 3075, 2980, 1635, 1340, 1175, 1050, 1035, 945, H NM (400 MHz, CD 3 ): δ 6.16 (t, J = 2 Hz, 1H), 4.18 (m, 2H), 3.97 (m, 2H), 2.39 (m, 2H), 2.16 (m, 2H). 13 C NM (100 MHz, CD 3 ): δ 128.3, , 122.8, 63.8, 30.2, Bromo-7-methyl-l,4-dioxaspiro[4,4]o-6-ee (2b) 5. White solid; mp ºC; I (ν max, cm -1 ): 2949, 2889, 1637, 1176, 1024, 948, H NM: (400 MHz, CD 3 ): δ (m, 2H), (m, 2H), (m, 2H), (m, 2H), 1.80 (s, 3H). 13 C NM: (100 MHz, CD 3 ): δ 144.1, 118.9, 118.1, 65.6, 34.3, 32.7, Bromo-l,4-dioxaspiro[4,5]dec-6-ee (2c) 5. Light yellow oil; bp ºC (1 mm); I (ν max, cm -1 ): 2949, 2890, 1637, 1437, 1352, 1176, 1156, 1110, 1070, 950 ad H NM: (400 MHz, CD 3 ): δ 6.34 (t, 1H, J = 5.4 Hz), (m, 2H), (m, 2H), (m, 2H), (m, 2H), (m, 2H). 13 C NM: (100 MHz, CD 3 ): δ 135.9, 124.4, 105.6, 65.6, 35.4, 27.3, Bromo-7-methyl-l,4-dioxaspiro[4,5]dec-6-ee (2d) 5. White solid; mp ºC; I (ν max, cm -1 ): 2949, 2889, 1637, 1176, 1024, 948, H NM: (400 MHz, CD 3 ): δ (m, 2H), (m, 2H), (m, 2H), (m, 2H), 1.79 (s, 3H), (m, 2H). 13 C NM: (100 MHz, CD 3 ): δ 141.2, 124.5, 104.6, 53.5, 37.3, 24.5, Geeral procedure for the Wurtz-Fittig couplig silylatio reactios Chlorotrimethylsilae (1.3mL, g, 10 mmol) was added to a stirred solutio of fiely cut sodium pieces (0.15 g, g atoms) suspeded i 5 ml ahydrous diethyl ether. The reactio flask was cooled i a cryolator at -40 ºC. Ice cold startig material 2a-2d (2.5 mmol) i 1 ml ahydrous ether was added to the mixture, ad the stirrig cotiued for aother hour. The mixture was the allowed to attai room temperature overight with cotiuous stirrig, whe a blue coloratio developed. Moitorig by gas chromatography idicated complete disappearace of the startig material. The precipitated solids ad ureacted sodium were filtered out o a plug of glass wool ad washed with dry ether (2 5mL). The combied ethereal extracts were washed with ice-cold saturated NaHC 3 solutio (20 ml) ad brie (20 ml) ad the dried (a. MgS 4 ). Vacuum cocetratio ad distillatio yielded the products 4a-4d. 2-Trimethylsilylcyclopeteoe (4a) 4. Colourless liquid; bp: bath 60 ºC (5 mm); I (ν max, cm -1 ) 2956, 2929, 2872, 1714, 1599, 1455, 1279, 1250, 1018, 868, 839, H NM: (400 MHz, CD 3 ): δ 7.78 (s, 1H), 2.65 (t, 2H, J = 2.04 Hz), 2.34 (t, 2H, J = 3.1Hz), 0.17 (s, 9H). 13 C NM: (100 MHz, CD 3 ): δ 213.7, 172,1, 147.3, 35.1, 30.3, HMS: Calculated for C 10 H 14 Si [M+Na] + = ; foud = Trimethylsilyl-3-methylcyclopeteoe (4b) 5. Pale yellow liquid. bp: bath 50 ºC (1.0 mm); I (ν max, cm -1 ): 2955, 2913, 1705, 1690, 1592, 1436, 1259, 1144, H NM: (400 MHz, CD 3 ): δ 2.49 (t, 2H, J = 5.1 Hz), 2.26 (t, 2H, J = 5.1Hz), 2.10 (s, 3H), 0.14 (s, 9H). 13 C NM: (100 MHz, CD 3 ): δ 214.2, 185.4, 139.4, 35.8, 35.5, 20.2, GC-MS: m/z (%): 168 (12), 154 (15), 153 (100), 137 (4), 112 (4), 111 (23), 97 (10), 83 (8), 75 (28), 74 (9), 59 (7), 43 (10). H- MS: Calculated for C 9 H 16 Si [M+Na] + = ; foud = Page 200

8 Geeral Papers AKIVC 2012 (vi) Trimethylsilylcyclohexeoe (4c) 4. White solid; mp: ºC (mp ºC); I (ν max, cm -1 ): 2593, 2895, 1665, 1592, 1427, 1349, 1161, 1126, 862, H NM: (400 MHz, CD 3 ): δ 7.10 (t, 1H, J = 3.77 Hz), 2.32 (m, 2H), 2.27 (m, 2H), 1.91 (q, 2H, J = 6.5Hz), 0.05 (s, 9H). 13 C NM: (100 MHz, CD 3 ): δ 202.6, 158.3, 141.7, 38.5, 27.1, 22.7, H-MS: Calculated for C 9 H 16 Si [M+Na] + = ; foud = Trimethylsilyl-3-methylcyclohexeoe (4d) 5. Pale yellow liquid, bp: bath 50 ºC (1.0 mm); I (ν max, cm -1 ): 2952, 2870, 1656, 1584, 1246, 1270, 855, 844, H NM: (400 MHz, CD 3 ): δ 2.33 (t, 2H, J = 6.4 Hz), 2.28 (t, 2H, J = 6.5 Hz), 1.99 (s, 3H), 1.89 ( q, 2H, J = 6.4 Hz), 0.19 (s, 9H). 13 C NM: (100 MHz, CD 3 ): δ 201.4, 167.7, 134.8, 36.1, 32.9, 23.0, 20.4, 0.0. m/z (%): 182 (2.06), 167 (100), 154 (5.1), 139 (10.3), 111 (5.15), ad 91 (4.1). H-MS: Calculated for C 10 H 18 Si [M+Na] ; foud Geeral procedure for preparatio of 2-(hydroxydimethylsilyl)cycloalk-2-eoes (5a-5d) To a magetically stirred mixture of 10 mmol equivalets of ahydrous Al 3 i dry dichloromethae cooled to -15 ºC i a ice-salt bath was added 1 mmol equivalet of 2- trimethylsilylcycloalkeoes (4a-4d) i 5 ml of dry dichloromethae dropwise over a period of 30 mi. The, saturated NaHC 3 (20 ml) was added ad stirred for aother 30 miutes ad the reactio mixture was simultaeously allowed to attai room temperature. The orgaic layer was separated ad washed with saturated NaHC 3 solutio (2 20 ml) ad brie (20 ml). The orgaic extract was dried (Na 2 S 4 ), cocetrated ad distilled (twice) uder reduced pressure to obtai the pure 2-(hydroxyldimethylsilyl)cycloalk-2-eoes 5a-5d. 2-(Hydroxydimethylsilyl)cyclopet-2-eoe (5a). Colourless liquid; bp: bath 40 ºC (1 mm); I (ν max, cm -1 ): 3348, 2956, 2926, 2852, 1662, 1591, 1512, 1351, 1250, H NM: (400 MHz, CD 3 ): δ 7.38 (t, 1H, J = 8 Hz), 3.16 (t, 2H, J = 8 Hz), 2.70 (t, 2H, J = 8 Hz), 1.25 (s, 1H), 0.00 (s, 6H). 13 C NM: (100 MHz, CD 3 ): δ 213.7, 172,1, 147.3, 35.1, 30.3, H-MS: Calculated for C 7 H 12 2 Si [M+Na] ; foud: (Hydroxydimethylsilyl)-3-methylcyclopet-2-eoe (5b). Colourless liquid; bp: bath 40 ºC (1 mm); I (ν max, cm -1 ): 3416, 2958, 2924, 1686, 1592, 1258, 1047, H NM (400 MHz, CD 3 ): δ (m, 4H), 2.16 (s, 1H), 2.08 (s, 3H), 0.00 (s, 6H). 13 C NM (100 MHz, CD 3 ): δ 214.2, 185.4, 139.4, 35.8, 35.5, 20.2, H-MS: Calculated for C 8 H 14 2 Si [M+Na] ; foud: (Hydroxydimethylsilyl)cyclohex-2-eoe (5c). Colourless liquid; bp: bath 40 ºC (1 mm). I (ν max, cm -1 ): 3409, 2955, 2929, 1651, 1592, 1354, 1248, 1165, 885, 775, H NM: (400 MHz, CD 3 ): δ 7.30 (t, 1 H, J = 3.8 Hz), (m, 4 H), (m, 2 H), 1.69 (s, br, 1H), (s, 6 H). 13 C NM: (100 MHz, CD 3 ): δ 202.7, 159.3, 141.2, 136.5, 38.5, 27.1, 22.7, 1.0. H-MS: Calculated for C 7 H 14 2 Si [M+Na] ; foud: (Hydroxydimethylsilyl)-3-methylcyclohex-2-eoe (5d). Colourless liquid; bp: bath 40 ºC (1 mm). I (ν max, cm -1 ): 3474, 2932, 2868, 1667, 1390, 1256, 1098, H NM: (400 MHz, CD 3 ): δ 4.46 (s, 1H), (m, 4 H), 2.03 (s, 3 H), (m, 2 H), 0.32 (s, 6H). Page 201

9 Geeral Papers AKIVC 2012 (vi) C NM: (100 MHz, CD 3 ): δ 205.9, 171.9, 134.5, 37.7, 34.1, 25.0, 21.9, 2.4. H-MS: Calculated for C 9 H 16 2 Si [M+Na] ; foud: Experimet to idetify the evolutio of CH 4 gas To a magetically stirred mixture of 10 mmol equivalets of ahydrous Al 3 i dry dichloromethae cooled to -15 ºC o a ice-salt bath was added 1 mmol equivalet of 2- trimethylsilylcycloalkeoes i 5 ml of dry dichloromethae dropwise over a period of 30 mi. The, the solvet was freeze-evaporated usig high vacuum to isolate a brow amorphous solid. The brow amorphous solid was take i a two ecked roud bottom flask fitted with a droppig fuel ad a rubber tube edig i a iverted glass tube for dowward displacemet of water. Water was added to the brow amorphous solid through the droppig fuel, to check for evolutio of methae gas if ay. I our reactio apparatus employed, there was foud to be o evolutio of methae gas. Supplemetary Material Available Copies of the I, 1 H NM, 13 C NM, ad H-MS for compouds 4a-5d are attached. Ackowledgemets ur grateful thaks are due to (1) Dr. Liam. Cox, Uiversity of Birmigham, Edgbasto, Birmigham, Great Britai, for all the help redered; (2) the rgaic Chemistry Departmet, Idia Istitute of Sciece, Bagalore; (3) Departmet of Sciece ad Techology, Govermet of Idia, New Delhi ad (4) the Uiversity Grats Commissio, Govermet of Idia, New Delhi for fiacial assistace, Grat F. No /2008(S). efereces 1. (a) Preseted i part at the Iteratioal Coferece o Curret Treds i Chemistry ad Biochemistry, ICCTCB-2009, Cetral College Campus, Bagalore Uiversity, Bagalore. Forms part of the Ph. D. thesis of D.J. (b) Prelimiary commuicatio: Divya Jyothi, HariPrasad, S. Sythetic Commu. 2009, eview o α-acylviyl aioic sythos: Chichilla,.; Najera, C. Chem. ev. 2000, 100, Shipe, W. D.; Sorese, E. J. J. Am. Chem. Soc. 2006, 128, Shih, C.; Fritze, L. E.; Sweto, J. S. J. rg. Chem. 1980, 45, Alimardaov, A.; Negishi, E. I. Tetrahedro Lett. 1999, 40, Page 202

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Copper-catalyzed Electrophilic Polyhydroamination of Internal Alkynes

Supportig Iformatio (SI) Copper-catalyzed Electrophilic Polyhydroamiatio of Iteral lkyes ezhao He, Yogwei Wu, ju Qi,, ad e Zhog Tag,, Guagdog Iovative Research Team, State Key Laboratory of Lumiescet Materials