Theoretical Studies on the Mechanism of Water-dependent Chemoselectivity in the Pt-Catalyzed Hydrative Cyclization of 2-Enynylbenzaldehydes

doi:10.7503/cjcu20150649

Abstract

Abstract:

With the aid of density functional theory(DFT) calculations, we made a detailed mechanism study on the origin of chemoselectivity in Pt-catalyzed hydrative cyclizations of 2-enynylbenzaldehydes. The calculations indicate that the formation of platinum-pyrylium intermediate is initiated by the activation of alkyne. Successive [3+2] cycloaddition with a double bond leads to the platinum-carbene complex. After that, the reaction proceeds along either pathway Ⅰ or pathway Ⅱ to yield products 3a and 4a, depending on the subsequent two-step water-assisted proton-transfer process. The calculated barrier leading to product 3a is 146.5 kJ/mol. For the formation of product 4a, the tautomerization(from enol to keto form) is the rate-determining step with a barrier of 185.8 kJ/mol when one water molecule is involved. However, when two and three water molecules are involved in catalysis, the barrier is reduced to 128.1 and 64.9 kJ/mol respectively. Therefore, the reaction preferentially proceeds along the pathway Ⅱ leading to product 4a. Water molecules that act as a cocatalyst in the tautomerization process are mainly responsible for the good selectivity. This result rationalizes well the experimental observations and provides a new insight into the Pt-catalyzed hydrative cyclizations.

Key words: PtCl2 catalysis, Chemoselectivity, Hydrative cyclization, Mechanism, Density functional thoery

CLC Number:

O641

TrendMD:

GUO Jinxin, ZHU Rongxiu, ZHANG Dongju, LI Mingxia, LIU Chengbu. Theoretical Studies on the Mechanism of Water-dependent Chemoselectivity in the Pt-Catalyzed Hydrative Cyclization of 2-Enynylbenzaldehydes[J]. Chem. J. Chinese Universities, 2015, 36(11): 2262.

Figures/Tables 8

Scheme 1 PtCl2-catalyzed hydrative cyclization of 2-enynylbenzaldhydes reported by Chang et al.[1]

Scheme 2 Proposed mechanism for formation of 4a reported by Chang et al.[1]

Scheme 3 Schematic geometries for the formation of platinium-carbene complex IM3 The values in parentheses are calculated relative free energies(kJ/mol) in toluene solution.

Fig.1 Calculated free energy(kJ/mol) profile in toluene solution for the formation of 3a-PtCl2 along pathway I

Fig.2 Geometric structures for intermediates and transition states in pathway Ⅰ(formation of 3a) Bond lengths are in nm.

Fig.3 Calculated free energy(kJ/mol) profile in toluene solution for the formation of 4a-PtCl2 along pathway II

Fig.4 Geometric structures for intermediates and transition states in pathway Ⅱ(formation of 4a) Bond lengths are in nm.

Table 1 Calculated partial natural bond orbital(NBO) charges on three structures TS44a, TS4'4a and TS4″4a

Structure	NBO charge/e
Structure	C1	C2	O1	H	Pt	O2
TS4^4a	0.44	-0.27	-0.77	0.51	0.63	-0.90
TS4'^a	0.49	-0.32	-0.75	0.49	0.62	-0.92
TS4″^4a	0.57	-0.37	-0.70	0.44	0.64	-0.93

References 41

[1]	Chang H. O., Sung M. L., Chang S. H., Org. Lett., 2010, 12(6), 1308—1311
[2]	Chang H. O., Ji H. L., Sung M. L., Chang S. H., Hyun J. Y., Chem. Eur. J., 2009, 15(1), 71—74
[3]	Lewis J. C., Bergman R. G., Ellman J. A., Acc. Chem. Res., 2008, 41(9), 1013—1017
[4]	Kirsch S. F., Synthesis, 2008, 20, 3183—3204
[5]	Meldal M., Tornϕe C. W., Chem. Rev., 2008, 108(8), 2952—3015
[6]	Michelet V., Toullec P. Y., Genêt J. P., Angew. Chem. Int. Ed., 2008, 47(23), 4268—4276
[7]	Patil N., Yamamoto Y., Chem. Eur. J., 2008, 14(18), 5381—5382
[8]	Majumdar K. C., Debnath P., Roy B., Heterocycles, 2009, 78(11), 2661—2728
[9]	Sohel S. M. A., Liu R. S., Chem. Soc. Rev., 2009, 38(8), 2269—2281
[10]	Liu Y. X., Zhang D. J., Bi S. W., Liu C. B., Org. Biomol. Chem., 2013, 11(2), 336—343
[11]	Liu Y. X., Zhang D. J., Bi S. W., Organometallics, 2012, 31(21), 4769—4778
[12]	Liu Y. X., Zhang D. J., Bi S. W., J. Phys. Chem. A, 2010, 114(49), 12893—12899
[13]	Liu Y. X., Zhang D. J., Gao J., Liu C. B., Chem. Eur. J., 2012, 18(48), 15537—15545
[14]	Shin S., Gupta A.K., Rhim C. Y., Oh C. H.,Chem. Commun., 2005, 4429—4431
[15]	Crone B. Kirsch S. F., Chem. Eur. J., 2008, 14(12), 3514—3522
[16]	Arcadi A., Chem. Rev., 2008, 108(8), 3266—3325
[17]	Li Z., Brouwer C., He C., Chem. Rev., 2008, 108(8), 3239—3265
[18]	Gorin D. J., Sherry B. D., Toste F. D., Chem. Rev., 2008, 108(8), 3351—3378
[19]	Fürstner A., Chem. Soc. Rev., 2009, 38(11), 3208—3211
[20]	Hashmi A. S. K., Angew. Chem. Int. Ed., 2010, 49(31), 5232—5241
[21]	Shintani R., Nakatsu H., Takatsu K., Hayashi T., Chem. Eur. J., 2009, 15(35), 8692—8694
[22]	Bai Y., Fang J., Ren J., Wang Z., Chem. Eur. J., 2009, 15(36), 8975—8978
[23]	Frisch M., Trucks G., Schlegel H., Scuseria G., Robb M., Cheeseman J., Montgomery Jr. J., Vreven T., Kudin K., Burant J., J. Chem. Phys., 1993, 98(7), 5648—5652
[24]	Miehlich B., Savin A., Stoll H., Preuss H., Chem. Phys. Lett., 1989, 157(3), 200—206
[25]	Lee C., Yang W. T., Parr R. G., Phys. Rev., 1988, 37(2), 785—789
[26]	Stephens P. J., Devlin F. J., Chabalowski C. F., Frisch M. J., J. Phys. Chem., 1994, 98(45), 11623—11627
[27]	Frisch M.J., Trucks G. W., Schlegel H. B., Scuseria G. E., Robb M. A., Cheeseman J. R., Montgomery J. A., Vreven T. Jr., Kudin K. N., Burant J. C., Millam J. M., Iyengar S., Tomasi S. J., Barone V., Mennucci B., Cossi M., Scalmani G., Rega N., Petersson G. A., Nakatsuji H., Hada M., Ehara M., Toyota K., Fukuda R., Hasegawa J., Ishida M., Nakajima T., Honda Y., Kitao O., Nakai H., Klene M., Li X., Knox J. E., Hratchian H. P., Cross J. B., Bakken V., Adamo C., Jaramillo J., Gomperts R., Stratmann R. E., Yazyev O., Austin A. J., Cammi R., Pomelli C., Ochterski J. W., Ayala P. Y., Morokuma K., Voth G. A., Salvador P., Dannenberg J. J., Zakrzewski V. G., Dapprich S., Daniels A. D., Strain M. C., Farkas O., Malick D. K., Rabuck A. D., Raghavachari K., Foresman J. B., Ortiz J. V., Cui Q., Baboul A. G., Clifford S., Cioslowski J., Stefanov B. B., Liu G., Liashenko A., Piskorz P., Komaromi I., Martin R. L., Fox D. J., Keith T., Al-Laham M. A., Peng C. Nanayakkara Y., Challacombe M., Gill P. M. W., Johnson B., Chen W., Wong M. W., Gonzalez C., Pople J. A., Gaussian 03, Revision D.01, Gaussian Inc., Wallingford CT, 2004
[28]	Hay P. J., Wadt W. R., J. Chem. Phys., 1985, 82(1), 270—283
[29]	Hay P. J., Wadt W. R., J. Chem. Phys., 1985, 82(1), 299—310
[30]	Wadt W. R., Hay P. J., J. Chem. Phys., 1985, 82(1), 284—298
[31]	Fukui K., J. Phys. Chem., 1970, 74(23), 4161—4163
[32]	Fukui K., Acc. Chem. Rev., 1981, 14(12), 363—368
[33]	Soriano E., Marco-Contelles J., Acc. Chem. Res., 2009, 42(8), 1026—1036
[34]	McKeown B. A., Gonzalez H. E., Friedfeld M. R., Brent Gunnoe T., Cundari T. R., Sabat M., J. Am. Chem. Soc., 2011, 133(47), 19131—19152
[35]	Tapia O., J. Math. Chem., 1992, 10(1), 139—181
[36]	Tomasi J., Persico M., Chem. Rev., 1994, 94(7), 2027—2094
[37]	Simkin B.Y., Sheikhet I., Quantum Chemical and Statistical Theory of Solutions: A Computational Approach, Ellis Horwood, London, 1995
[38]	Cossi M., Barone V., Cammi R., Tomasi J., Chem. Phys. Lett., 1996, 255, 327—335
[39]	Barone V., Cossi M., Tomasi J., J. Comput. Chem., 1998, 19(4), 404—417
[40]	Li H., Wang X., Huang F., Lu G., Jiang J., Wang Z. X., Organometallics, 2011, 30(19), 5233—5247
[41]	Takano Y., Houk K. N., J. Chem. Theory Comput., 2005, 1(1), 70—77