Stereodivergent Synthesis of β-Heteroatom-Substituted Vinyl­silanes by Sequential Silylzincation–Copper(I)-Mediated Electrophilic­ Substitution

Abstract

Sulfur-, oxygen-, and phosphorus-substituted terminal alkynes undergo regio- and stereoselective silylzincation by reaction with (Me₂PhSi)₂Zn, (Me₃Si)₃SiH/Et₂Zn or [(Me₃Si)₃Si]₂Zn/Et₂Zn. The addition across the C–C triple bond always occurs with β-regioselectivity but the stereoselectivity is tunable: (Me₂PhSi)₂Zn for cis and (Me₃Si)₃SiH/­Et₂Zn or [(Me₃Si)₃Si]₂Zn/Et₂Zn for trans. The procedures making use of the zinc reagents (Me₂PhSi)₂Zn and [(Me₃Si)₃Si]₂Zn can be combined in one-pot with a subsequent stereoretentive copper(I)-mediated electrophilic substitution of the intermediate C(sp²)–Zn bond. These stereodivergent protocols offer a regio- and stereoselective access to trisubstituted vinylsilanes decorated with sulfur-, oxygen-, and phosphorus substituents with either double-bond geometry.

Key words

copper - silylmetalation - silylzinc reagents - vinylsilanes - zinc

• References

• 1 Lim DS. W, Anderson EA. Synthesis 2012; 44: 983

For an account, see:
• 2a Barbero A, Pulido FJ. Acc. Chem. Res. 2004; 37: 817
• 2b For the original work, see: Fleming I, Newton TW, Roessler F. J. Chem. Soc., Perkin Trans. 1 1981; 2527
• 3a Hayami H, Sato M, Kanemoto S, Morizawa Y, Oshima K, Nozaki H. J. Am. Chem. Soc. 1983; 105: 4491
• 3b Okuda Y, Morizawa Y, Oshima K, Nozaki H. Tetrahedron Lett. 1984; 25: 2483
• 3c Liepins V, Karlström AS. E, Bäckvall J.-E. J. Org. Chem. 2002; 67: 2136
• 4 Nakamura S, Uchiyama M, Ohwada T. J. Am. Chem. Soc. 2004; 126: 11146
• 5 Okuda Y, Wakamatsu K, Tückmantel W, Oshima K, Nozaki H. Tetrahedron Lett. 1985; 26: 4629
• 6a Hibino J.-i, Nakatsukasa S, Fugami K, Matsubara S, Oshima K, Nozaki H. J. Am. Chem. Soc. 1985; 107: 6416
• 6b Fugami K, Hibino J.-i, Nakatsukasa S, Matsubara S, Oshima K, Utimoto K, Nozaki H. Tetrahedron 1988; 44: 4277
• 7 Auer G, Oestreich M. Chem. Commun. 2006; 311
• 8a Vercruysse S, Cornelissen L, Nahra F, Collard L, Riant O. Chem. Eur. J. 2014; 20: 1834
• 8b Shintani R, Kurata H, Nozaki K. J. Org. Chem. 2016; 81: 3065
• 9 For a recent review, see: Basheer A, Marek I. Beilstein J. Org. Chem. 2010; 6: No. 77
• 10 Capella L, Capperucci A, Curotto G, Lazzari D, Dembech P, Reginato G, Ricci A. Tetrahedron Lett. 1993; 34: 3311
• 11 Yasui H, Yorimitsu H, Oshima K. Bull. Chem. Soc. Jpn. 2008; 81: 373
• 12 Huang X, Xu L. Synthesis 2006; 231
• 13 1-Alkoxyalkynes: Murakami M, Amii H, Takizawa N, Ito Y. Organometallics 1993; 12: 4223
• 14 1-Phenylthioalkynes: Casson S, Kocienski P, Reid G, Smith N, Street JM, Webster M. Synthesis 1994; 1301

Ynamides:
• 15a Timbart L, Cintrat J.-C. Chem. Eur. J. 2002; 8: 1637
• 15b Naud S, Cintrat J.-C. Synthesis 2003; 1391
• 16 Ynamides: Saito N, Saito K, Sato H, Sato Y. Adv. Synth. Catal. 2013; 355: 853

The Cu(I)-catalyzed addition of silicon nucleophiles released from Si–B interelement compounds is known but without C(sp²)–B bond formation, see:
• 17a Arylsulfonylalkynes: Linstadt RT. H, Peterson CA, Lippincott DJ, Jette CI, Lipshutz BH. Angew. Chem. Int. Ed. 2014; 53: 4159
• 17b Ynamides: Vercruysse S, Jouvin K, Riant O, Evano G. Synthesis 2016; 48: 3373
• 18 Fopp C, Romain E, Isaac K, Chemla F, Ferreira F, Jackowski O, Oestreich M, Perez-Luna A. Org. Lett. 2016; 18: 2054
• 19 Romain E, Fopp C, Chemla F, Ferreira F, Jackowski O, Oestreich M, Perez-Luna A. Angew. Chem. Int. Ed. 2014; 53: 11333
• 20 Computational evidence for such a mechanism was reported for the silylzincation of 1-phenylallene with Me₃SiZnMe, see: Yonehara M, Nakamura S, Muranaka A, Uchiyama M. Chem. Asian J. 2010; 5: 452

Such a mechanism is reminiscent of the trans-selective radical carbozincation of alkynes with dialkylzinc reagents, see:
• 21a Maury J, Feray L, Bertrand M. Org. Lett. 2011; 13: 1884
• 21b Chemla F, Dulong F, Ferreira F, Nüllen M, Pérez-Luna A. Synthesis 2011; 1347
• 21c Chemla F, Dulong F, Ferreira F, Pérez-Luna A. Beilstein J. Org. Chem. 2013; 9: 236
• 22 The C–S bond is a useful handle for further elaboration, see: Unsinn A, Dunst C, Knochel P. Beilstein J. Org. Chem. 2012; 8: 2202
• 23 The α-carbamoyloxy-substituted vinylcopper species arising from 4f was found to decompose within 1 h at –78 °C. It is likely that, with electrophiles less reactive than allyl bromide, decomposition is faster than electrophilic substitution.
• 24 The structure of 19 was unambiguously established by comparison with an independently prepared sample, see: Feldman KS, Saunders JC, Wrobelski ML. J. Org. Chem. 2002; 67: 7096
• 25 Trisubstituted β-alkyl α-copper enol carbamates have been reported to be stable at temperatures lower than –30 °C suggesting that the presence of the silicon moiety contributes to the chemical instability of 4f and 4g, see: Chechik-Lankin H, Marek I. Org. Lett. 2003; 5: 5087
• 26 Cubillo de Dios MA, Fleming I, Friedhoff W, Woode PD. W. J. Organomet. Chem. 2001; 624: 69
• 27 Alexakis A, Cahiez G, Normant J.-F, Villieras J. Bull. Soc. Chim. Fr. 1977; 693
• 28 CCDC 1494398 [(Z)-26] contains the supplementary crystallographic data for this paper. These data can be obtained free of charge from the Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_request/cif.
• 29 (Me₂PhSi)₂Zn was used as an almost LiCl-free ethereal solution prepared according to: Vyas DJ, Oestreich M. Chem. Commun. 2010; 46: 568
• 30 Dobrovetsky R, Kratish Y, Tumanskii B, Botoshansky M, Bravo-Zhivotovskii D, Apeloig Y. Angew. Chem. Int. Ed. 2012; 51: 4671