. Dry, 1 H, 13 C, 29 Si, and 31 PNMR spectra were recorded with Advance 300, 400, or 500 spectrometers . 1 H, 29 Si, and 13 CNMR chemical shifts are reported in ppm relative to SiMe 4 as internal standard. 31 PNMR downfield chemical shifts are expressed in ppm relative to 85 %H 3 PO 4 . 1 Hc orrelation spectra were obtained by using standard procedures

3. Hz, C. H. 1h, C. Hsi, and J. Hh, 43 (s, 9H,3 CH 3 tBu ), 1.62 (d, J HH = 6.4 Hz, 3H, CH 3 iPr ), 1.76 (s, 9H, p.79602551

1. Hz, C. H-iprsept, J. Hh-=-6-hz, 1. , 1. et al., 08 ppm (m, 2H,H Ar ); 13 CNMR (100.62 MHz, C 6 D 6 ,2 58C): d = 5.0 (s, CH 3Si (s, CH 3Si ), 22.5 (s, CH 2bridgeheadCN9 (s, CH 3 iPr ), 25.6 (s, CH 3 iPr ), 26.3 (s, CH 3 iPr ), 27.1 (s, CH 3 iPr ), 28.1 (s, CH iPr ), 28.2 (s, CH iPr, 47.2 (d, J PC = 13.9 Hz, PCCH bridgehead ), 47.4 (s, CHSi), 48.1 (d, J CP = 16 Hz, NCCH bridgehead ), 51.7 (d, J CP = 2.5 Hz, C tBu ) 123.0 (d, J CP = 21.4 Hz, PC=CH), pp.6395-6399, 2002.

N. Si, 49 MHz, C 6 D 6 ,2 5 8C): d = À54.6 ppm (d, J SiP = 20.8 Hz, À4.81 ppm (d, J PSi = 8.5 Hz, SiMe); 31 PNMR (161.98 MHz, C 6 D 6 ,258C): d = 49.2 ppm (s)

J. Hh-=-7hz, 3. , and C. H. 1h, After stirring for 24 ha t8 08C, all volatiles were removed under vacuum. The resulting solid was washed with pentane to give 6 as an analytically pure white powder (46 mg, 74 %) Suitable crystals of 6 for X-ray diffraction analysis were obtained by crystallization from ab enzene solution Decomposition point = 155 8C Derivative 6 was also obtained by the direct reaction of silacyclopropylidene 1 (60 mg, 0.067 mmol) with benzaldehyde (13.6 mL, 0.134 mmol) in toluene (0.6 mL) at À80 8C After stirring for 30 min at À80 8C, the mixture is warmed to room temperature. Then, all volatiles were removed under vacuum. The resulting solid was washed with pentane to give the analytically pure white powder of 6 (51 mg, 65 %) 1 HNMR (500.13 MHz, CD 2 Cl 2 ,2 58C): d = 0.44 (s, 3H,CH 3 Si), 0.53 (s, 3H,C H 3 Si, Cyclic sila-ester 6:As olution of sila-b-lactam 3 (60 mg toluene (0.6 mL) was heated at 80 8C 3H,C H 3 iPr ), 1.40 (d, J HH = 6.5 Hz, 3H, CH 3 iPr ), 1.48 (s, 9H,3CH 3 tBu, pp.74722879939609-7

J. Cp-=-3-hz, J. Ch-iprd, . Cp-=-ch-ars, . Ch-ars, . Ch-ars et al., 1 (s, CH 3 iPr ), 25.3 (s, CH 3 iPr ), 26.2 (s, CH 3 iPr ), 26.7 (s, CH 3 iPr ), 27.5 (d, J CP = 2.1 Hz, CH 2CbridgeheadCP0 (s, CH 2bridgeheadCN, 13 CNMR (75.47 MHz, CD 2 Cl 2 34.3 (s, 3CH 3 tBu ), 45.4 (d, J CP = 10.8 Hz, CH 2Norb ), 47.9 (d, J CP = 14.6 Hz, NCCH bridgehead ), 48.7 (d, J CP = 15.8 Hz, PCCH bridgehead ) 127.0 (d, J CP = 2.9 Hz, CH Ar ), 127.5 (d, J CP = 2.0 Hz, CH Ar ), 127.7 (s, CH Ar ) À6.5 ppm (d, J SiP = 9.3 Hz, SiMe); 31 PNMR (202.46 MHz, CD 2 Cl 2 ,258C): d = À57.7 ppm (s), pp.141-149

P. Hz, J. Bridgeheadd, . Cp-=-5-hz, J. Ch-2norbd, J. Cp-=d et al., 7 (br,C H Ar ), 123.0 (s, CH Ar, 145.5 (s, CH Ar ), 147.5 (s, C Ar ) 164.7 ppm (d, J CP = 9.2 Hz, PC=CN); 29 Si NMR (59.62 MHz): d = À42.2 ppm (d, J SiP = 33.9 Hz, Si = O), À0.87 ppm (s, SiMe); 31 PNMR (121.49 MHz, CDCl 3 ,2 58C): d = 26.6 ppm (s)

1. Pyridine and C. H. =ch, DMAP (0.024 g, 0.198 mmol), and 4-chloro- benzaldehyde (0.014 g, 0.10 mmol) at À40 8C After 20 min at À40 8C, the solution was allowed to warm to room temperature and stirred for 10 min. The mixture was then heated at 80 8Cf or 24 h. The resulting cis-aryl olefins were purified by flash column chromatography (eluting:p entane/ethyl acetate 9.5:0.5). cis-4- Chlorostilbene was obtained as ac olorless oil in 72 %y ield. Spectral data obtained for this compound corresponded to previously reported data, p.93

J. =. Pyridined, 2. , C. Ar, 1. , C. H. =ch-2h et al., 015 g, 0.10 mmol) at À40 8C After 20 min at À40 8C, the solution was allowed to warm to room temperature . The mixture was stirred at room temperature for 18 h and then at 80 8Cf or 24 h. The resulting cis-aryl olefins were purified by flash column chromatography (eluting:p entane/ethyl acetate 9.5:0.5). cis-4-Dimethylaminostilbene was obtained as ac olorless oil in 45 %yield. Spectral data obtained for this compound corresponded to previously reported data, pp.59-66

2. Hz, C. Ar, 2. , C. Ars, C. Ars et al., 49 MHz, C 6 D 6 ,2 5 8C): d = 39.9 (s, 2CH 3 ), pp.13-75

S. J. Onnon, S. Blechert, S. J. Malcolmson, S. J. Meek, A. R. Zhugralin et al., Phi-and omega-scans were used. The data were integrated with SAINT [35] and an empirical absorption correction with SADABS was applied. [36] The structures were solved by direct methods by using ShelXS-97 (6)o rb yu sing the intrinsic phasing method (ShelXT) (3 and 8) [37] and refined by using the least-squares method on F 2 (ShelXL) [38] All non-H atoms were refined with anisotropic displacement parameters. The Ha toms were refined isotropically at calculated positions using ar iding mode and 1457558 (8)c ontain the supplementary crystallographic data for this paper.T hese data can be obtained free of charge from The Cambridge Crystallographic Data Centre Selected data for 3:C 55 H 71 N 4 OPSi 2 , M r = 891.30, monoclinic, space group P2 1 /c, a = 16 580 parameters, 0restraints, R1[I > 2s(I)] = 0.0451, wR2[ all data] = 0.1190, largest diff. peak and hole:0 .373 and À0.364 eŠ À3 . Selected data for 6:C 65 H 88 N 3 O 4 PSi 2 , M r = 1062.53, triclinic, space group P1 ¯ , a = 13)8, g = 71, triclinic, space group P1 ¯ , a = 10 Angew.C hem.I nt, AXS kappa APEX II CCD Quazar diffractometer (3 and 6)e quipped with a3 0Wair-cooled microfocus source, or with aBruker-AXS D8- Venture equipped with aC MOS Area detector using Mo Ka radiation) Š, b = 12.7922(4) Š, c = 22.9537(8) Š, b = 91.3971(18)8, V = 4950) Š, a = 75.009(2)8, b = 68)8, V = 3013, pp.1469229-565, 2000.

. Chem and . Int, 8; e) S, Angew. Chem, vol.49, issue.1223, 2010.

C. Blechert, . Revf-)-s, and M. K. Otha, 97;g )A.F ürstner, Tetrahedron Science, vol.20121, issue.341, p.357, 2012.

D. Astruc, 848;b )Y .C hauvin, Angew.C hem. Int, New J. Chem. Angew.Chem, vol.30, issue.118, p.3824, 2006.

R. R. Schrock, A. H. , and A. Int, 592; Angew.C hem, Angew.Chem, vol.4244, issue.118, p.74037483832, 2003.

P. Schwab, M. B. Rance, J. W. Ziller, R. H. , and A. Hem, 039; Angew.C hem, Int. Ed. Engl. Organometallics, vol.342, issue.16, pp.179-3867, 1995.

T. Troadec, M. Lopez-reyes, R. Odriguez, A. , N. Merceron et al., Donor-Stabilized Silacyclobutanone: A Precursor of 1-Silaketene via Retro-[2 + 2]-Cycloaddition Reaction at Room Temperature, Journal of the American Chemical Society, vol.138, issue.9, p.2965, 2016.
DOI : 10.1021/jacs.6b00631

R. Rodriguez, D. Gau, T. Kato, N. Saffon-merceron, A. De-cózar et al., Angew.C hem.I nt, pp.840-1040, 2011.

A. Stalke, S. Int, S. Yao, J. D. Inoue, M. Pping et al., 963; Angew.C hem. 2013, 125, 3036;c )Y .X iong, Angew.C hem. Int. Ed. Angew.Chem, vol.52, issue.125, p.5271477287, 2013.

V. K. Aggarwal, J. R. Fulton, C. G. Sheldon, and J. De-vicente, Selectivity with Semi-stabilizing Groups in Wittig Olefinations, Journal of the American Chemical Society, vol.125, issue.20, p.6034, 2003.
DOI : 10.1021/ja029573x

H. Yamataka and T. Hanafusa, Relative reactivity and stereoselectivity in the Wittig reactions of substituted benzaldehydes with benzylidenetriphenylphosphorane, The Journal of Organic Chemistry, vol.57, issue.10, p.2865, 1992.
DOI : 10.1021/jo00036a021

M. Das, D. F. O-'shea, . Org, and . Lett, ] SAINT,P rogram for data reduction, 2016.

Y. Zhao and D. G. Truhlar, The M06 suite of density functionals for main group thermochemistry, thermochemical kinetics, noncovalent interactions, excited states, and transition elements: two new functionals and systematic testing of four M06-class functionals and 12 other functionals, Theoretical Chemistry Accounts, vol.103, issue.1-3, p.215, 2008.
DOI : 10.1002/ijch.199300041