2,2-Divinyladamantane : A New Substrate for the Modification of Silicon Surfaces

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2,2-Divinyladamantane : A New Substrate for the Modification of Silicon Surfaces
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  Pergamon Tetrahedron 54 (1998) 11899-l 1906 TETRAHEDRON 2 2-Divinyladamantane : A New Substrate for the Modification of Silicon Surfaces Luc Giraud,* Vroni Huber and Titus Jenny UrGersite de Fribourg, Institut de Chimie Organique, P&olles. CH-1700 Fribourg, Switzerland Received 1 April 1998; accepted 24 April 1998 Abstract : 2,2-Divinyladamantane has been readily obtained in six steps from 2-adamantanone. The key steps were a Wittig-Homer-Emmons reaction, an ortho ester Claisen rearrangement using the microwave heating technique and a selenoxide elimination. Q 1998 Elsevier Science Ltd. All rights reserved. INTRODUCTION The surface of silicon has been studied intensively for many years because of its paramount importance in modem technology. At the beginning of the 90’s, the first textured diamond films were grown on silicon (100) substrates by microwave plasma CVD (Chemical Vapour Deposition) using a bias-enhanced nucleation process ’ and in 1993 the first oriented diamond film was deposited on silicon (100) 2. Nucleation is increased by the presence of carbon molecules or clusters on the substrate surface which should act as seeds for the diamond nuclei, and Matsumoto 3 and Olah 4 suggested hydrocarbon cage molecules such as adamantane as possible embryos for diamond nuclei formation in the gas phase. In 1993 Linford and Chidsey reported the first example of a densely-packed, stable organic monolayer covalently bonded directly to the silicon surface 5. RESULTS AND DISCUSSION Consequently, we decided to synthetise a new derivative of adamantane containing two alkene chains allowing for an oriented, bidentate connection to the silicon (111) surface (Figure) by silicon-carbon bonds 6. * Fax ++41 (0)26 300 97 39; E-mail anne.giraud@unifr.ch 0040-4020/98/ - see front matter Q 1998 Elsevier Science Ltd. All rights reserved. PII: S00404020(98)00724-8  11900 L. Giraud et al. / Tetrahedron S4 1998) I1 899-l 1906 Formation of the Si-C bond from the reaction of an olefin with a silicon hydride surface may be achieved by adapting one of the known techniques, e.g. radical-mediated hydrosilylation of olefins with molecular silanes 7 , photochemical hydrosilylation of olefins with trichlorosilane ‘, or hydrosilylation of olefins catalyzed by transition metals complexes 9. Adamantane structure Silicon surface (111) In this communication we report the synthesis of 2,2divinyladamantane, obtained in 6 steps from adamantanone in 38% overall yield (Scheme I), as a new substrate for the nucleation of oriented diamond growth on a silicon (111) surface. The crucial step in this synthesis is the formation of a quatemary center for which a Claisen rearrangement lo was chosen. Wittig-Horner-Emmons reaction _ ortho ester Claisen rearrangement Scheme 1 Thus, Wittig-Homer-Emmons reaction I1 of 2-adamantanone with triethyl phosphonoacetate using sodium hydride as base in dry THF, followed by reduction of the resultant ester zyxwvutsrqponmlkjihgfedcbaZYXWVUT , with AlH3 l2 made in situ by the addition of LiAlIQ to a solution of AlC13 in THF at O’C, furnished the ally1 alcohol 2 in over 86 % yield (Scheme 3). LiAlQ l3 in TIIF at room temperature and at 0°C or DIBAH l4 in CH2Cl2 at -80°C reduced the conjugated ester 1 to a mixture of the allylic alcohol 2 and the corresponding saturated alcohol 3 in a respective ratio of 78/22,91/9 and 90110 (Scheme 2).  L. Giraud et al. / Tetrahedron 54 1998) 11899-l 1904 zyxwvutsrqponmlkjihgfedcbaZYX 1901 ’ C02E1 L r mH + &GH 1 2 9 scheme 2 zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA Table 1 Selectivity of the reduction of the a&unsaturated ester 1 Reductor Solvent Temperature Ratio of product@ Yield (%)b) 2 I 3 of alcohol 2 AM3 THF r.t. 100 0 94 Liw TI-IF r.t. 78 22 73 THF 0°C 91 9 77 DIBAH CH2Cl2 -80°C 90 10 72 a) Ratio of products 2 and 3 determined by GC with a temperature program isotherm at 120 T. b) Yields are of isolated and purified products. The microwave heating technique ‘5&j was used for carrying out the ortho ester Claisen rearrangement (Johnson method’s) l7 . Irradiation of a solution of the allylic alcohol 2, with an excess of triethyl orthoacetate and a catalytic amount of propionic acid in dry DMF in an adapted domestic microwave oven operating at full power (650 W at 2450 MHz) furnished the y&unsaturated ester 4. The ability to form a y&unsaturated ester as well as the ease with which a quaternary center is created in a one pot reaction are two advantages of this Claisen rearrangement. Subsequent reduction of the ester function with LiAl& in THF gave the alcohol 5 in a yield of over 59% (Scheme 3). MKVW, EtCO,H, DMF uv. 1 h 61 - Sahoma 3 1 C02Et 4 / ”c-w.t. 94 -LP H 2 LiAIHI / MF 0”c-N.t. -& OH 97% 6 Although the conversion of the hydroxy ethyl side chain into the second vinyl substituent (5 + 7) seems to constitute a trivial synthetic operation, all our attemps to prodtice 7 by elimination of the corresponding mesylate either failed (using DBU) or resulted in substitution (using sodium methylate as the base). Flash pyrolysis of the corresponding acetate at 650°C only led to partial cofiversion. Finally tiatement of the primary  11902 L. Giraud et al. / Tetrahedron 54 1998) 11899-I 1906 alcohol 5 with o-nitro-phenyl selenocyanate 18*19 n THF at room temperature in the presence of tri-n- butylphosphine resulted in good yield (83%) of the primary alkyl selenide 6. Oxydation of the selenide 6 with sodium metaperiodate 20*21 ave the selenoxide which eliminates seleninic acid at room temperature to give the desired olefin 7 in 90% yield (Scheme 4). / OH zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA 5 6 7 CONCLUSION We have presented a rapid and efficient procedure for the multigram-scale synthesis of 2,2- divinyladamantane from 2-adamantanone. The synthesis is based on the ortho ester Claisen rearrangement and the selenoxyde elimination. The hydrosilylation reaction between the silicon (111) surface, or molecular silanes and 2,2-divinyladamantane is presently being studied and the results will be presented elsewhere. EXPERIMENTAL SECTION THF and Et20 were freshly distilled from Na/benzophenone under an argon atmosphere prior to use; CH2Cl2, DMF and benzene were distilled from Cal-l2 under N2 and toluene from Na under N2. Solvents for chromatography were used after distillation. Flash column chromatography (FC) and filtration were performed with Baker silica gel 0.063-0.200 mm). TLC were run on Merck silica gel 60 F254 analytical plates; detection were carried either with UV, iodine, spraying with a solution of 25 g phosphomolybdic acid, 10 g Ce(NH&(N03)~4H20,60 ml cont. H2SO4 and 940 mL Hz0 with subsequent heating, or with a solution of 3 g KMn04, 20 g K2CO3, 300 mL of Hz0 and 5 mL of NaOH 5%, followed by heating. Melting points were determined on a Reichert therrnovar apparatus. IR: spectra were recorded on a Mattson Unicam 5000 spectrophotometer; in cm-l. NMR: Bruker Avance DRX-500 1H 500.13 MHz and 13C 125.77 MHz); for 1H 6 in ppm relative to CDCl3 (= 7.27 ppm ), for 13C 6 in ppm relative to CDCl3 (= 77.1 ppm), and coupling constants J are given in Hz. 1H NMR splitting patterns abbreviations are: s, singlet; d, doublet; t, triplet; q, quartet; m, multiplet; br., broad. 13C NMR multiplicities were determined by the APT and DEPT sequences, abbreviations are: q. CH3; r, CH2; d, CH; s, quaternary carbons. Assignements were confirmed by NOESY, COSY and HETCOR experiments. MS: Vacuum Generators Micromass VG 70/7OE DS 1 I-250; EI 70 eV); m/z a). Elemental analysis: Ciba specialities Mikrolabor, Marly, Switzerland. Gas chromatographic quantitative analyses were carried out on a Fisons HRGC MEGA 2 series gas chromatograph equipped with a Permabond SE 54 25 m x 0.32 mm capillary column.  L. Giraud et al. /Tetrahedron 54 (I 998) 11899-l 1906 11903 Adamantan-2-ylidene-acetic acid ethyZ ester I). A solution of triethyl phosphonoacetate (22 mL, 110 mmol) in 50 mL of dry THF was added to a suspension of NaH (4.9 g, 206 mmol) in 3 mL of THF at 0 “C. The mixture was stirred at room temperature for 1 h and then cooled to -78 “C. To this was added 2- adamantanone (5 g, 33 mmol) in 15 mL THF over 10 min. The resulting mixture was stirred at -78 “C for 6 h and allowed to warm to room temperature. It was poured into 200 mL of 1:l ether-NH&l and the phases were separated. The organic layer was washed with water and the combined aqueous phases were extracted with Et20 (3 x 100 mL). The combined extracts were dried over MgS04, filtered and concentrated under reduced pressure to afford 16.5 g of a yellow oil. Flash chromatography on silica gel with hexane/AcOEt (98 : 2) afforded 6.7 g (91%) of 1 as a colorless liquid. 1H NMR (CDC13): 6 = 5.58 (s, lH, CH=), 4.13 (q, J = 7.1, 2H, OCH H3), 4.05 (br.s, lH, C(3)-H), 2.43 (br.s, lH, C(l)-H), 1.96 (br.s, 2H, C(5)-H, C(7)-H), 1.96-1.92 (m, 4H, C(4)- H syn. C(8)-H,,,, C(9)-&,,, C(lO)-H,,,), 1.86 (br.s, C(6)H2), 1.86-1.81 (m, 4H, C(4)-H,,?i, C(8)-Hanti, C(9)-Hantip C(lO)-Ha&, 1.27 (t, J = 7.1, 3H, OCH2CH3). 13C NMR (CDC13): S = 171.6 (s, CO2), 166.5 (s, C 2)), 108.5 d, CH=), 58.9 (t, OCHz), 41.1 (d, C(l)), 39.9 (t, C(S), C(9)), 38.9 (t, C(4), C(lO)), 36.6 (t, C(6)), 32.5 (d, C(3)), 27.7 (d, C(5), C(7)), 14.0 ( q, CH3). EI-MS: m/z (%) = 220 (76, kf+), 191 (17), 174 (100) 146 (43) 105 (72) 91 (86), 77 (75). Anal. Calcd for Ct4H2oO2 (220.31) : C, 76.33; H, 9.15. Found : C, 77.03; H, 9.39. Adamantan-2-ylidene-ethanol 2). To a stirred suspension of AlH3, made in situ by the addition of LiAlI-I4 (6.2 g, 164 mmol) to a solution of AlCl3 (7.3 g, 55 mmol) in THF (40 mL) under N2 in an ice bath, was added a solution of ester 1 (6.0 g, 27 mmol) in THF (20 mL) with a syringe within ca. 30 min. Stirring was continued for 3 h at 0 “C before the mixture was allowed to warm up to r.t. After addition of MeOH (3 mL), the precipitate formed was filtered. The aqueous layer was extracted with Et20 (3 x 100 mL), dried over MgS04 and evaporated in vacua. The residue was purified by flash chromatography (hexane/EtzO 1 : 1) to yield 6.10 g (94%) of alcohol 2. 1H NMR (CDCl3): 6 = 5.21 (d, J = 7.0, lH, CH=), 4.02 (t, J = 7.0, 2H, CHzOH), 3.18 (br.s, lH, OH), 2.77 (br.s, lH, C(3)-H), 2.28 (br.s, lH, C(l)-H), 1.96 (br.s, 2H, C(5)-H, C(7)-H), 1.91 (br.d, J = 11.6, 2H, C(4)-H,,, C(lO)-H,,,), 1.88 (brd, J = 13.1, 2H, C(8)-H,,,, C(9)-H,&, 1.79 (brd, J = 13.1, 2H, C(S)-H,,ti, C(9)-Ha,ti), 1.72 (brd, J = 11.6, 2H, C(4)-H,,ri, C(lO)-H,,ri). t3C NMR (CDC13): s= 151.3 (s, C(2)), 115.6 (d, CT-I=), 57.5 (t, OCH2), 40.12 (d, C(l)), 39.5 (t, C(8), C(9)), 38.8 (t, C(4), C(lO)), 36.9 (t, C(6)), 32.2 (d, C(3)). 28.3 (d, C(5), C(7)). EI-MS: m/z (%) = 178 (25, M+), 149 (38) 135 (82) 105 (35) 91 (SO), 79 (100). 55 (39). Anal. Calcd for Cl2HlsO (178.27) : C, 80.85; H, 10.18; Found : C, 80.63; H, 10.11. Adamantan-d-ethanol 3). To a stirred suspension of LiAlIQ (1.14 g, 30.0 mmol) in THF (10 mL) under N2 in a ice bath, was introduced a solution of ester 1 (6 g, 27.2 mmol) in THF (10 mL) with a syringe within ca. 30 min. The mixture was stirred for further 3 h at 0 “C and allowed to warm up to r.t. After addition of MeOH (2 mL), the precipitate formed was filtered. The aqueous layer was extracted with Et20 (3 x 100 mL), dried over MgS04 and evaporated in vacua. Purification by flash chromatography (hexane/EtzO 1 : 1) gave 3.7 g (77%) of alcohol 2 and 0.4 g (8%) of alcohol 3. 1H NMR (CDCl3): 6 = 3.53 (t, J = 6.9, 2H, CH20), 3.16 (br.s, lH, OH), 2.44 (br.s, lH, C(l)-H), 1.90 (br.d, J = 11.5, 2H, C(8)-Hsyn, C(9)-H,&, 1.86 (br.s, lH, C(5)-H), 1.85 (brd, J = 13.0, 2H, C(4)-HJyn, C(lO)-H&, 1.82 (m, lH, C(2)-H), 1.79 (br.s, lH, C(7)-H), 1.73 (br.d, J = 11.5, 2H, C(S)-H,,ri, C(9)-Ha , 1.72 (br.s, 2H, C(6)H2), 1.71 (m, CH2CH20). 1.67 (br.s, lH, C(3)-H), 1.52 (br.d, J = 13.0, 2H, C(4)-Ha,,i, C(lO)-Ha,&. ‘3C NMR (CDC13): S= 60.1 (t,
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