2760
J.
Org. Chem. 1992,57, 2760-2762 from Prof.A.
Mourifio (Santiago de Compostela, Spain)are gratefully acknowledged.
Registry No. (h)-(E)-la, 57549-92-5; (&)-@)-la, 57549-93-6; (E)-16,23726-91-2; (Z)-16,23726-92-3; 2a, 127-41-3; 2b, 79-77-6; 5a, 52610-46-5; (E)-5b, 124099-60-1; (Z)-5b, 139608-99-4; 6, 42741-51-5; 7a, 37079-64-4; (&)-7b, 139609-00-0; 8a, 139609-01-1; (&)-8b (isomer l ) , 139609-02-2; (lt)-8b (isomer 2), 139684-74-5; 9a, 139609-03-3; (&)-9b (isomer l), 139609-04-4; (&)-9b (isomer
Supplementary Material Available: NMR spectra of 8b and 9b (6 pages). Ordering information is given on any current masthead page.
2), 139686-52-5.
1,3-Bis(trimethylsilyl)propene as 1,3- and 2-Aryl- 1,3-bis(trimethylsilyl)propenes with
Elect rop hiles
3,3-Propene Dianion Synt hons. Reactions of
Wu-Wang Weng and Tien-Yau Luh*
Department of Chemistry, National Taiwan University, Taipei, Taiwan 10764, Republic of China
Received January 2, 1992
Whereas allylsilanes and vinylsilanes can be considered as allyl anion and vinyl anion synthons,l 1,3-bis(tri- methylsily1)propene (1) which contains both functionalities could couple with an electrophile El to give either 2a or 2b. Further reaction of the latter species with a second electrophile E2 could afford 1,3-substitution product 3a or the isomeric 3,3-substitution product 3b (Scheme
I).2
Given this versatility it is surprising that the chemistry of 1 has not been explored more extensively. The reactions of 1 or its derivatives with carbonyl compounds under different conditions leading to the correspondingdiene^,^
substituted allylsilanes4p5 and vinylsilanes6 have been re- ported. The formation of 4 by treatment of 1 with tri- methylsilyl chlorosulfonate appears to be the only known example of using 1 as a 1,3-propene dianion synthon 5a.7 Recently, we reported a facile synthesis of 2-aryl-1,3- (bistrimethylsily1)propenes 7 from the corresponding or- thothioesters 6 (eq 1).8 The availability of these com- pounds prompted our exploration of using 7 as 1,3- and 3,3-propene dianion synthons 5a and 5b.6 7 a A r = P h
b Ar = 1-Naphthyl c Ar = 2-Naphthyl d Ar = 4-MeC6H,
(1) Chan, T. H.; Fleming, I. Synthesis 1979, 761. Sakurai, H. Pure Appl. Chem. 1982, 54, 1. Hosomi, A. Acc. Chem. Res. 1988, 21, 200. (2) The Lewis acid-catalyzed regioselective a-attack of allylsilanes with carbon electrophiles has been extremely rare. An ester group at the y-position is required to promote such a reaction, and a first silyl group migration from carbon to oxygen has been suggested. Cf. Chan, T.-H.; Kang, G. J. Tetrahedron Lett. 1982,23, 3011.
( 3 ) Trost, B. M.; Brandi, A. J. Org. Chem. 1984,49, 4811.
(4) House, H. 0.; Gaa, P. C.; Lee, J. H. C.; VanDerveer, D. J. Org. Chem. 1983,48, 1670.
(5) Fleming, I.; Langley, J. A. J. Chem. SOC., Perkin Trans. 1 1981,
1421.
(6) Corriu, R.; Escudie, N.; Guerin, C. J. Organomet. Chem. 1984,264,
207.
(7) Grignon-Dubois, M.; Pillot, J. P.; Dunogues, J.; Duffaut, N.; Calas,
R. J. Organomet. Chem. 1977,124, 135.
(8) (a) Tzeng, Y.-L.; Luh, T.-Y.; Fang, J.-M. J. Chem. SOC., Chem. Commun. 1990,399. (b) For a review, see: Luh, T.-Y. Acc. Chem. Res. 1991, 24, 257. Scheme I E l Me,Si -SiMe3 3a 1 E l 2b Me3SiOS02-S03SiMe3 --- = -4 Sa 5b
Results and Discussion
When a mixture of
E-
and 2-isomers of 2-aryl-1,3-bis- (trimethylsily1)propenes 78 was treated with 2 equiv of N-bromosuccinimide (NBS) in CH2C12 at -78 "C, (2)-2- aryl-l,3-dibromopropenes 8 were obtained in satisfactory yields (TableI,
entries 1-4). The stereochemical assign- ments of 8 are based on NOE experiments. The formation of 8 is stereoselective regardless of the stereochemistry of the starting materials 7. Thus, the reaction of (E)-7a withNBS
under the same conditions afforded 8a in 71% yield.Br Ar
%Br q S i M e , ~~,si+SiMe,
Ar Ar H
8 9 10
Treatment of 7 with 1 equiv of NBS under the same conditions afforded the monobromo products 9 in satis- factory yields (Table
I,
entries 5-8). These results indi- cated that the first reaction of 7 proceeds via the typical allylsilane reaction pattern. The bromonium ion inter- mediate 10 is postulated. Hence, the carbon-silicon bond a t C-3 in 10 is apparently more labile giving the a-bro- moallylsilane 9 selectively.The reaction of a-haloallylsilanes with electrophiles has been briefly in~estigated.~ Exposure of 9a to NBS in CH2C12
at
-78 "C yielded 8a (entry 9). The interaction of the carbon-silicon bond with the empty p-lobe in in- termediate 1 la leading to the double-bond formation may account for the stereoselectivity of this reaction. Presum- ably, the conformer l l a is more stable than llb.9Br +E Ar 11 a R = Ph, R' = CH2Br b R = CH2Br, R' = Ph 12 a E = MeCH(OE1)- b E = Me(CH2)&O- c E = PhCH(0H)-
The TiC1,-mediated reactions of 9a with 1,l-diethoxy- ethane afforded 12a (entry 10). Similarly, treatment of 9a with hexanoyl chloride at -60 "C yielded 12b (entry 11). These observations indicated that 1,3-silylpropenes 7 be- have in the manner of two overlapped and transposed allyl silanes. In other words, 7 can be considered as a 1,3- propene dianion synthon 5a. In fact, it is possible
to
carryout the two reactions in one pot, by allowing 7a to react
(9) Hosomi, A.; Ando, M.; Sakurai, H. Chem. Lett. 1984, 25, 1385.
0022-3263/92/ 1957-2760$03.00/0 0 1992 American Chemical Society
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Notes
J . Org. Chem., Vol. 57, No. 9, 1992 2761 dianion synthons. Sequential replacement of the silyl groups by different electrophiles can readily be achieved.Table 1. Reaction of 7 and 9 with Electrophiles product entry substr electrophile condnsa (% yield)
1 7a NBS A 8a (70) 2 7b NBS A 8b (74) 3 7c NBS A 8c (75) 4 7d NBS A 8d (61) 5 7a NBS B 9a (74) 6 7b NBS B 9b (56) 7 7c NBS B 9c (72) 8 7d NBS B 9d (62) 9 9a NBS B 8a (79) 10 9a MeCH(OEt)2 C 12a (90) 11 9a Me(CH2)4COCl D 12b (65) 12 9a Me3CCl E 13a (68) 13 9a EtMe2CCl E 13b (57) 14 9a PhCH(Me)Br C 14 (65) O A : 2 equiv of NBS, -78 "C, 2 h. B: 1 equiv of NBS, -78 "C, 2
h. C: TiC14/CH2C12, -78 OC, 0.5 h. D TiC14/CH2C12, -60 "C, 0.5
h. E: TiC14/CH2C12, -78 O C , 2 h.
first with 1 equiv of
NBS
in CH2C12 a t -78 OC and then with TiCl, (1.1. equiv) and 1,l-diethoxyethane. The ether 12a was obtainedin
50% yield. Similarly, 12b wasisolated
in 41% yield.Treatment of 9a with tert-alkyl chlorides
in
the presence of TiCl, at -78 "C afforded ipso-substituted products (entries 12 and 13). The reaction of 9a with (a-bromo- ethy1)benzene afforded 14 in 65% yield (entry 14). Ap-13 a E = Me&- 14 b E = EiMe2C- c E = PhCH(Me)- 16 a E = Me&- 17 b E = E1Me2C- c E = PhCH(Me)- 15 Ph 18
parently, the intermediate 13c may further undergo in- tramolecular Friedel-Crafts reaction under the reaction conditions. The yields and the selectivity of the reactions did not change with the order of the addition of the electrophile and TiClk These results suggest that 1,3- disilylpropenes 7 also serve as a 3,3-propene dianion
syn-
thon Sbe2 The ipso substitution reaction is somewhat interesting, but the origin of such selectivity is unclear. Presumably, the aryl group in 9a may have some kind of the directive effect. Indeed, 1S9 was allowedta
react with tert-butyl chloride, tert-amyl chloride, and (a-bromo- ethy1)benzene at -78 "C in the presence of TiCl,to
give 16a( E / Z
=
48/52), 16b(E/Z
= 46/54), and 16c(E/Z
= 43/57) in 42,48, and 63% yields, respectively.No
trace amount of 17 was obtained at all.Fluoride ion-mediated reactions of 9 with electrophiles do not show the same regioselectivity. For example, treatment of 9a with benzaldehyde in the presence of CsF (1.1 equiv) and HMPA (1.1 equiv)l0 in refluxing THF
afforded
12c and epoxides 18(E2
= 1:l)in
25% and 53% yield, respectively.In summary, we have established the first systematic examples of using l,&disilylpropene as 1,3- or 3,bpropene
(10) Kessar, S. V. Pure Appl. Chem. 1990,62, 1397.
Experimental Section
General Procedure for the Bromination of 2-Aryl-1,3- bis(trimethylsily1)propene with NBS. To a solution of 7& (1.00 "01) in CH2C12 (5 mL) under N2 at -78 "C was added NBS
(1.00 or 2.00 mmol), and the mixture was stirred at -78 "C for 2 h, quenched with 10% aqueous Na2S103 (10 mL), and diluted with CH2Clz (10 mL). The organic layer waa washed with water (10 mL X 3) and dried (MgSOS. After evaporation of the solvent in vacuo, the residue was chromatographed on silica gel (hexane) to afford the desired product. Compounds 8a-8d and 9a-9d were
prepared according to the general procedure above.
(2)- 1,3-Dibromo-2-phenyl-l-propene (Sa). Reaction of 7a
( E / Z = 34/66,131 mg, 0.50 mmol) and NBS (179 mg, 1.00 mmol)
in CHzClz (5 mL) gave 8a (97 mg, 70%): 'H NMR (CDCld 6 4.48 (s,2 H), 6.61 (a, 1 H), 7.25-7.50 (m, 5 H); '%
NMR
(CDClJ 6 30.5, 110.5, 126.3,128.7,128.8, 137.8,141.9; MS m/z (re1 intensity) 278 (35), 276 (65), 274 (35), 195 (65), 165 (100); HRMS calcd for C$18Br2 275.8970, found 275.8982. Reaction of 9a (21 mg, 0.08 m o l ) and NBS (14 mg, 0.08 "01) in CHzC12 ( 5 mL) also gave 8a (17 mg, 79%).(Z)-l,3-Dibromo-2-( 1-naphthyl)-1-propene (8b). Reaction of 7b (E/Z = 25/75, 70 mg, 0.22 mmol) and NBS (79 mg, 0.44
"01) in CH2C12 (5 mL) gave 8b (53 mg, 74%): 'H
N M R
(CDCld6 4.52 (8, 2 H), 6.50 (s, 1 H), 7.45-7.55 (m, 4 H), 7.70-7.91 (m, 3 H); '%
N M R
(CDClJ 6 32.7,112.0,124.7,125.2,126.1,126.6,127.1,128.5, 129.0, 131.2,133.7, 135.7,141.2; MS m/z (re1 intensity) 328 ( l l ) , 326 (22), 324 (ll), 245 (41), 165 (100); HRMS calcd for C13H1&r2 325.9126, found 325.9121. Anal. Calcd C, 47.89; H, 3.09. Found: C, 47.74; HI 3.09.
(2)-1,3-Dibromo-2-(2-naphthyl)-l-propene (&). Reaction of 7c
(E/Z
= 50/50,312 mg, 1.00 mmol) and NBS (358 mg, 2.00 mmol) in CHzC12 ( 5 mL) gave 8c (245 mg, 75%): 'H NMR (CDClJ 6 4.58 (s,2 H), 6.79 (e, 1 H), 7.32-7.60 (m, 3 H), 7.62-7.95 (m, 4 H); '% NMR (CDCl,) 6 30.5,110.9,123.8,125.7,126.6,126.7, 127.6,128.3,128.5,133.1,133.2,134.9,141.8; MS m / z (re1 intensity) 328 (261,326 (48), 324 (261,245 (17),16 (100); HRMS calcd for C13H1&r2 325.9126, found 325.9135. Anal. Calcd: C, 47.89; HI 3.09. Found: C, 47.42; H, 3.06.(2)- 1,3-Dibromo-2-( 4-met hylpheny1)- 1-propene (8d). Re- action of 7d
(E/Z
= 34/66, 138 mg, 0.50 mmol) and NBS (179mg, 1.00 "01) in CH2C12 (5 mL) gave 8d (88 mg, 61%): 'H
N M R
quartet, J = 8 Hz, 4 H); l% NhfR (CDClJ 6 21.1,30.7,109.7,126.2,129.5, 134.8, 138.7, 141.7; MS m / z (re1 intensity) 292 (44), 290
(881, 288 (441, 209 (381, 130 (100); HRMS calcd for CloHl&r2 289.9126, found 289.9134. Anal. Calcd C, 41.42; H, 3.47. Found C, 41.64; H, 3.66.
3-Bromo-3-(trimethylsilyl)-2-phenyl-l-propene (9a). Re-
action of 7a (80 mg, 0.30 mmol) and
NBS
(54 mg, 0.30 mmol) in CHzC12 (5 mL) gave 9a (60 mg, 74%): 'H NMR (CDC13) 6 0.05 (8, 9 H), 4.38 (8, 1 H), 5.38 (8, 1 H), 5.49 (s, 1 H), 7.24-7.48 (m, 141.5,148.1; MS m / z (re1 intensity) 270 (76), 268 (70), 255 (30), 189 (40), 73 (100); HRMS calcd for C12Hl,BrSi 268.0283, found 268.0282. Anal. Calcd: C, 53.53; H, 6.38. Found: C, 53.90; H, 6.68.3-Bromo-34 trimet hylsily1)-2- ( 1 -napht hy1)- 1-propene (9b). Reaction of 7b (126 mg, 0.40 mmol) and NBS (72 mg, 0.40 mmol) in CH2C12 (5 mL) gave 9b (71 mg, 56%): 'H NMR (CDClJ 6 0.10 (8, 9 H), 4.23 ( 8 , 1 H), 5.47 (8, 1 H), 5.82 (8, 1 H), 7.28-7.60 (m, 4 H), 7.68-7.91 (m, 2 H), 8.17 (br d,
J
= 9 Hz, 1 H); 13C NMR 128.5, 131.0, 133.7, 140.2, 147.8; MS m / z (re1 intensity) 320 (6), 318 (5), 239 (loo), 165 (41), 73 (38); HRMS calcd for Cl6H1&rSi 318.0440, found 318,0427. Anal. Calcd C, 60.16; H, 6.00. Found C, 60.27; HI 6.52.j-Bromo-j-(trimet hylsilyl)-2-(2-naphthyl)- 1-propene (9~). Fieaction of 7c (312 mg, 1.00 "01) and NBS (179 mg, 1.00 "01) in CH2Clz ( 5 mL) gave 9c (230 mg, 72%): 'H NMR (CDClJ 6 0.04 (s, 9 H), 4.45 (s, 1 H), 5.56 (8, 2 H), 7.35-7.60 (m, 3 H), 7.72-7.95 (m, 4 H); 13C NMR (CDCl,) 6 -2.3, 42.9, 117.4, 125.2, 125.5, 126.1, 126.3, 127.6, 128.0, 128.1, 132.9, 133.1, 138.7, 148.0; (CDClJ 6 2.35 (s, 3 H), 4.47 (8, 2 H), 6.61 (8, 1 H), 7.12-7.38 (AB 5 H); 13C NMR (CDC13) 6 -2.4, 43.1, 116.8, 126.9, 127.9, 128.3, (CDC13) 6 -2.1,44.9, 119.9, 125.1, 125.8, 125.9,126.1, 126.3, 128.2,
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2762 J . Org. Chem., Vol. 57, No. 9, 1992
MS m/z (re1 intensity) 320 (82), 318 (78), 166 (loo), 73 (38);
H R M S
calcd for C16H18rSi 318.0440, found 318.0432. And. C d c d c , 60.16; H, 6.00. Found: C. 60.47; H, 5.96.3-Bromo-3-(trimethylsilyl)-2-(4-methylphenyl)-l-propene
(9d). Reaction of 7d (276 mg, 1.0 mmol) and NBS (179 mg, 1.0 mmol) in CH2C12 (5 mL) gave 9d (175 mg, 62%): 'H NMR (CDC13) 6 0.03 ( 8 , 9 H), 2.33 ( 8 , 3 H), 4.31 ( 8 , 1 H), 5.38 ( 8 , 1 H),
5.42 (s, 1 H), 7.11 (d, J = 8 Hz, 2 H), 7.28 (d, J = 8 Hz, 2 H); 13C 147.9; MS m/z (re1 intensity) 284 (63), 282 (59), 269 (17), 267 (17), 202 (loo), 130 (63),73 (78); HRMS calcd for C13H1J3rSi 282.0434, found 282.0430.
General Procedure for the TiCl,-Mediated Reaction of 9a with Electrophile. To a cold (-60 "C or -78 "C) solution of the electrophile (1.10 "01) and Tic& (1.10 mmol) in CH2C12 (5 mL)
was added dropwise a solution of 9a (1.10 mmol) in CH2C12 (5 mL). The mixture was stirred at -60 "C or -78 "C for 0.5-2 h, quenched with water, and diluted with CH2Clz (10 mL). The organic layer was washed with brine (10 mL), dried (MgSO,), filtered, and concentrated to give the residue which was chro- matographed on silica gel to afford the desired product. Com- pounds 12a, 12b, 13a, 13b, 14, and 16a-c were prepared by this procedure.
(Z)-l-Brom0-4-ethoxy-2-phenyl-l-pentene (12a). A solution of 9a (269 mg, 1.00 mmol), 1,l-diethoxyethane (130 mg, 1.10 mmol), and TiCl, (209 mg, 1.10 mmol) in CH2C12 (5 mL) was stirred at -78 "C for 0.5 h. After workup, the crude product was chromatographed on silica gel (hexane/CH2Clz = 1/11 to afford
12a (242 mg, 90%): lH NMR (CDCl,) 6 1.10 (t, J = 7 Hz, 3 H), 1.12 (d, J = 7 Hz, 3 H), 2.82 (dd, J = 7, 14 Hz, 1 H), 2.99 (dd, J = 6, 14 Hz, 1 H), 3.35-3.55 (m, 3 H), 6.41 ( 8 , 1 H), 7.24-7.41 (m, 5 H); 13C NMR (CDCl,) 6 15.4, 19.8, 40.0, 63.8, 73.5, 106.7, 126.6, 127.7, 128.4, 140.5, 143.9; MS m/z (re1 intensity) 270 (8), 268 (7), 189 (65), 73 (100); HRMS calcd for C13H17Br0 268.0463, found 268.0411. (Z)-l-Bromo-2-phenylnon-l-en-4-one (12b). A solution of
9a (269 mg, 1.00 mmol), hexanoyl chloride (148 mg, 1.10 mmol), and Tic& (209 mg, 1.10 mmol) in CHZCl2 (5 mL) was stirred at -60 "C for 0.5 h. After workup, the crude product was chroma- tographed on silica gel (hexane/CH2C12 = 1/4) to yield 12b (192 mg, 65%): 'H NMR (CDC13) 6 0.85 (t, J = 6 Hz, 3 H), 1.26 (m, 4 H), 1.59 (m, 2 H), 2.45 (t, J = 7 Hz, 2 H), 3.78 (s, 2 H), 6.65 ( 8 , 1 H), 7.24-7.36 (m, 5 H); 13C NMR (CDC13) 6 13.8, 22.3, 23.3,31.2, 42.2,47.9, 108.8, 126.2, 128.1, 128.7, 139.5, 139.8, 206.4; MS m / z
(re1 intensity) 296 (4), 294 (4), 215
(loo),
99 (13); HRMS calcd for ClSHlJ3r0 294.0620, found 294.0616.3-Bromo-4,4-dimethyl-2-phenyl-l-pentene (13a). A solution of 9a (100 mg, 0.37 mmol), tert-butyl chloride (38 mg, 0.41 mmol), and TiCl, (78 mg, 0.41 mmol) in CH2C12 (5 mL) was stirred at -78 "C for 2 h. After workup, the crude product was chroma- tographed on silica gel (hexane) to afford 13a (64 mg, 68%): 'H
1 H), 7.23-7.49 (m, 5 H); 13C
NMR
(CDCld 6 27.8,37.4,67.6,120.7, 127.1, 127.6,128.3,142.4,149.0; MS m/z (re1 intensity) 254 (15), 252 (13), 198 (71), 196 (65), 173 (43), 57 (100); HRMS calcd for C13H17Br 252.0514, found 252.0517.3-Bromo-4,4-dimethyl-2-phenyl-l-hexene (13b). A solution of 9a (100 mg, 0.37 mmol), tert-amyl chloride (44 mg, 0.41 mmol), and TiC1, (78 mg, 0.41 mmol) in CH2C12 (5 mL) was stirred at -78 "C for 2 h. After workup, the crude product was chroma- tographed on silica gel (hexane) to give 13b (57 mg, 57%): 'H
H), 1.20-1.50 (m, 2 H), 4.93 (s, 1 H), 5.44 (s, 1 H), 5.61 ( 8 , 1 H),
7.25-7.45 (m, 5 H); 13C NMR (CDC13) 6 8.3, 23.6, 24.7, 33.2, 39.9, 66.0,121.2,127.1, 127.5,128.3,130.9,148.9; MS m/z (re1 intensity) 268 (16), 266 (lo), 198
(loo),
196 (98), 71 (55); HRMS calcd for Cl4H1ar 266.0671, found 266.0662.2-Bromo-l,3-dimethyl-l-phenylindan (14). A solution of 9a
(135 mg, 0.50 mmol), 1-bromo-1-phenylethane (102 mg, 0.55 mmol), and TiC1, (105 mg, 0.55 mmol) in CH2Clz (5 mL) was stirred at -78 "C for 0.5 h. After workup, the crude product was chromatographed on silica gel (hexane) to yield 14 (98 mg, 65%): (dq, J = 6, 10 Hz, 1 H), 4.08 (d, J = 10 Hz, 1 H), 6.88 (d, J = 7 Hz, 1 H), 7.15-7.35 (m, 8 H); 13C NMR (CDC13) 6 16.0, 22.7,45.6, 54.1,71.6,122.8,124.4,126.8,127.3,127.4,127.5,128.2,143.4,145.3, NMR (CDCl3) 6-2.3, 21.1,43.1, 116.1, 126.7, 129.0, 137.7, 138.6, NMR (CDClJ 6 1.00 (8, 9 H), 4.88 ( 8 , 1 H), 5.45 ( 8 , 1 H), 5.61 (s, NMR (CDClJ 6 0.74 (t, 3 H, J = 7 Hz), 0.85 ( 8 , 3 H), 0.97 (9, 3 'H NMR (CDC13) 6 1.48 (d, J = 6
Hz,
3 H), 1.64 (9, 3 H), 3.39 Notes149.1; MS m/e (re1 intensity) 302 (62), 300 (68), 287
(W),
285 (1001, 221 (45); HRMS calcd for C17H17Br 300.0514, found 300.0523.l-Bromo-4,4-dimethyl-l-pentene (16a). A solution of 15 (386
mg, 2.00 mmol), tert-butyl chloride (204 mg, 2.20 mmol), and
Tic4
(418 mg, 2.20 mmol) in CHzC12 (5 mL) was stirred at -78 "C for2 h. After workup, the crude product was chromatographed on silica gel (pentane) to give 16a (149 mg, 42%,
E/Z
= 48/52)." Attempts to separate these isomers were unsuccessful. (E)-16a:'H NMR (CDCl,) 6 0.88 (s, 3 H), 1.89 (d, J = 6 Hz, 2 H), 5.96 (d, J = 14
Hz,
1 H), 6.14 (dt, J = 6,14Hz,
1 H); '3c NMR (CDClJ 6 29.1,30.9,47.1, 105.2, 132.3. (Z)-16a: 'H NMR (CDC13) 6 0.92 (s,9 H), 2.09 (d, J = 6 Hz, 2 H), 6.13 (d, J = 6 Hz, 1 H), 6.22 (dt, J = 10,6Hz,
1 H); '%N M R
(CDClJ 6 29.3,31.3,43.4,108.9,135.6. l-Bromo-4,4-dimethyl-l-hexene (16b). A solution of 15 (386 mg, 2.00 mmol), tert-amyl chloride (238 mg, 2.20 mmol), and T i c , (418 mg, 2.20 mmol) in CH2C12 (5 mL) was stirred at -78 "C for 2 h. After workup, the crude product was chromatographed on silica gel (pentane) to give 16b (181 mg, 48%,E/Z
= 46/54). Attempts to separate these isomers were unsuccessful. (E)-16b:'H NMR (CDC13) 6 0.81 (t, J = 6 Hz, 3 H), 0.87 (s,6 H), 1.24 (q, J = 6 Hz, 2 H), 2.09 (d, J = 8 Hz, 2 H), 5.96 (d, J = 14 Hz, 1 H), 6.15 (dt, J = 8, 14 Hz, 1 H); 13C NMR (CDCl3) 6 8.3, 26.3, 33.3, 34.0, 44.8, 105.1, 132.1. (Z)-16b: 'H NMR (CDC13) 6 0.82 (t, J = 6 Hz, 3 H), 0.84 ( 8 , 6 H), 1.19 (9, J = 6 Hz, 2 H), 1.89 (d, J = 7 Hz, 2 H), 6.10 (dt, J = 7,lO Hz, 1 H), 6.20 (d, J = 10 Hz, 1 H); 13C NMR (CDC13) 6 8.4, 26.5, 33.7, 34.3, 41.2, 108.8, 135.4. 1-Bromo-4-phenyl-1-pentane (16c). A solution of 15 (386 mg, 2.00 mmol), 1-bromo-1-phenylethane (374 mg, 2.20 mmol), and TiC1, (418 mg, 2.20 mmol) in CH2C12 (5 mL) was stirred at -78 "C for 0.5 h. After workup, the crude product was chroma- tographed on silica gel (hexane) to give 16c (284 mg, 63%,
E/Z
2.25-2.35 (m, 2 H), 2.78 (sextet, J = 7 Hz, 1 H), 5.85 -6.10 (m, 2 H), 7.24-7.55 (m, 5 H); 13C
NMR
(CDCld 6 21.3,39.4,41.5,105.3, 126.2, 126.9, 128.4, 136.3, 146.0; HRMS calcd for C11H13Br 224.0201, found 222.0211. (Z)-16c: 'H NMR (CDC13) 6 1.28 (d, J = 7 Hz, 3 H), 2.40-2.62 (m, 2 H), 2.86 (sextet, J = 7 Hz, 1 H), 5.97 (apparent q, 1 H, J = 7 Hz), 6.13 (d, 1 H, J = 7Hz),
7.24-7.55 (m, 5 H); 13C NMR (CDC13) 6 21.7, 38.1, 40.0, 108.6, 126.2,126.9, 128.4, 133.3, 146.3; HRMS calcd for Cl1Hl3Br 224.0201, found 222.0214.Reaction of 9a with Benzaldehyde and
CsF.
To a slurry of benzaldehyde (53 mg, 0.50 mmol), HMPA (150 mg, 0.55 mmol), and CsF (84 mg, 0.55 mmol) in THF (10 mL) was added dropwise9a (135 mg, 0.50 mmol), and the mixture was allowed to reflux for 16 h, quenched with water (20 mL), and extracted with CH2C12. The organic layer was dried (MgSO,) and evaporated to give a pale yellow residue which was chromatographed on silica gel using hexane/CH2C12 (1/1) as the eluent to give 18 (58 mg, 53%,
E/Z
= l/l). The column was then eluted with CH2C12 to give 12c (38
mg, 25%). 12c: 'H NMR (CDClJ 6 1.85 (d, J = 4 Hz, OH group), 3.04 (dd, J = 5, 14 Hz, 1 H), 3.25 (dd, J = 8, 14 Hz, 1 H), 4.81 (m, 1 H), 6.45 (s, 1 H), 7.24-7.36 (m, 10 H); 13C NMR (CDC13) 6 42.9, 72.5, 107.6, 125.8, 126.8, 127.7, 128.1, 128.4, 128.7, 140.0, 143.1,143.6; HRMS calcd for C&&fl302.0307, found 302.0282. = 2 Hz, 1 H), 5.45 (s, 1 H), 5.50 (s, 1 H), 7.21-7.44 (m, 10 H); 13C
128.6,137.0,137.8,144.0; HRMS calcd for C1&14O 222.1045, found
4.40 (d, 1 H, J = 4 Hz), 5.33 ( 8 , 1 H), 5.48 ( 8 , 1 H), 7.19-7.40 (m,
10 H); 13C NMR (CDC13) 6 59.7, 60.2, 114.3, 125.9, 126.9, 127.7, 127.9,128.4,134.2,137.8, 139.5; HRMS calcd for C&I14O 222.1045, found 222.1049.
Acknowledgment. This
work
is supported by theNational Science Council of t h e Republic of China.
Supplementary Material Available: 13C NMR spectra of
8a, 9d, 12a-c, 13a, 13b, 14, ( E ) - and (Z)-16c, ( E ) - and (Z)-lS,
and a mixture of (E)- and (Z)-16a and -16b (13 pages). Ordering information is given on any current masthead page.
= 43/57). (E)-16~: 'H NMR (CDC13) 6 1.24 (d, J = 7 Hz, 3 H),
(Z)-18: 'H NMR (CDCl3) 6 3.67 (d, J = 2 Hz, 1 H), 3.71 (d, J
NMR (CDCl3) 6 61.5,62.5, 112.1, 125.6,126.1, 128.1, 128.4, 128.5, 222.1049. (E)-18: 'H NMR (CDClJ 6 4.07 (d, 1 H, J = 4
Hz),
(11) Katvalyan, G. T.; Mistryukov, E. A. Izv. Akad. Nauk, SSSR, Ser. Khim. 1985, 2324. Chem. Abstr. 1986,105, 78800.
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