Oxidative Cleavage of Silyl Ethers by an Oxoammonium Salt

Jacob J. Loman; Vincent A. Pistritto; Christopher B. Kelly; Nicholas E. Leadbeater

doi:10.1055/s-0035-1561498

Synlett, Inhaltsverzeichnis

Synlett 2016; 27(16): 2372-2377
DOI: 10.1055/s-0035-1561498

letter

Oxidative Cleavage of Silyl Ethers by an Oxoammonium Salt

Jacob J. Loman ‡

^aDepartment of Chemistry, University of Connecticut, 55 North Eagleville Road, Storrs, CT 06269, USA eMail: nicholas.leadbeater@uconn.edu

,

Vincent A. Pistritto ‡

^aDepartment of Chemistry, University of Connecticut, 55 North Eagleville Road, Storrs, CT 06269, USA eMail: nicholas.leadbeater@uconn.edu

,

Christopher B. Kelly

^aDepartment of Chemistry, University of Connecticut, 55 North Eagleville Road, Storrs, CT 06269, USA eMail: nicholas.leadbeater@uconn.edu

,

Nicholas E. Leadbeater*

^aDepartment of Chemistry, University of Connecticut, 55 North Eagleville Road, Storrs, CT 06269, USA eMail: nicholas.leadbeater@uconn.edu

^bDepartment of Community Medicine & Health Care, University of Connecticut Health Center, The Exchange, 263 Farmington Ave, Farmington, CT 06030, USA

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Abstract

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^‡ These authors contributed equally

Abstract

A method for the oxidative cleavage of silyl ethers to their corresponding carbonyl species mediated by an oxoammonium salt is described. The resulting aldehydes and ketones are obtained under mild reaction conditions with no observed overoxidation. For robust substrates, heating to reflux temperatures significantly reduces the reaction time.

Key words

protecting groups - silicon - oxidation - oxoammonium salt - aldehydes - ketones

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Referenzen

References and Notes

Silyl protecting groups:

1a Greene TW, Wuts PG. M. Protective Groups in Organic Synthesis . 3rd ed. Wiley; New York: 1999
1b Corey EJ, Venkateswarlu A. J. Am. Chem. Soc. 1972; 94: 6190

2 Nelson TD, Crouch RD. Synthesis 1996; 9: 1031
3 DiLauro AM, Seo W, Phillips ST. J. Org. Chem. 2011; 76: 7352
4 Wang B, Sun H, Sun Z. J. Org. Chem. 2009; 74: 1781
5 Muzart J. Synthesis 1993; 11

Alternative oxidative deprotection strategies:

6a Firouzabadi H, Iranpoor N, Zolfigol MA. Bull. Chem. Soc. Jpn. 1998; 71: 2169
6b Karimi B, Rajabi J. Org. Lett. 2004; 6: 2841

7 Barnych B, Vatèle JM. Synlett 2011; 2048
8 Kelly CB, Lambert KM, Mercadante MA, Ovian JM, Bailey WF, Leadbeater NE. Angew. Chem. Int. Ed. 2015; 54: 4241
9 Mercadante MA, Kelly CB, Bobbitt JM, Tilley LJ, Leadbeater NE. Nat. Protoc. 2013; 8: 666
10 Richter H, García-Mancheño O. Eur. J. Org. Chem. 2010; 4460
11 Pradhan PP, Bobbitt JM, Bailey WF. J. Org. Chem. 2009; 74: 9524

12a Hamlin TA, Kelly CB, Leadbeater NE. Eur. J. Org. Chem. 2013; 3658
12b Kelly CB, Mercadante MA, Wiles RJ, Leadbeater NE. Org. Lett. 2013; 15: 2222
12c Bobbitt JM, Bartelson AL, Bailey WF, Hamlin TA, Kelly CB. J. Org. Chem. 2014; 79: 1055
12d Leadbeater NE, Bobbitt JM. Aldrichimica Acta 2014; 47: 65

13 Kelly CB, Ovian JM, Cywar RM, Gossland TR, Wiles RJ, Leadbeater NE. Org. Biomol. Chem. 2015; 13: 4255
14 Representative Procedure To a 100 mL round-bottom flask equipped with a stir bar was added the silyl ether 2c (1.95 g, 7.0 mmol, 1 equiv) and the oxoammonium salt 1 (2.10 g, 7.0 mmol, 1 equiv), followed by MeCN (35 mL, 0.2 M in the silyl ether). The solution was heated to 40 °C while stirring for 72 h. After this time, the crude mixture was diluted with Et₂O (200 mL) and deionized water (200 mL). The phases were separated, and the aqueous layer was extracted with Et₂O (3 × 50 mL). The combined organic layers were washed with deionized water (ca. 100 mL), brine (ca. 100 mL), and dried with Na₂SO₄. The solvent was removed in vacuo by rotary evaporation, and the resulting crude mixture was adhered to silica gel using 1.5 wt equiv of SiO₂ (relative to the theoretical yield). The dry-packed material was gently added atop a silica gel plug. The plug was washed with an excess of hexanes (ca. 5 column volumes). The desired product was eluted off the plug via a 95:5 by volume mixture of hexanes–EtOAc (3–4 column volumes). The solvent was removed in vacuo by rotary evaporation affording the pure aldehyde 3c (0.67 g, 59%) as a clear yellow liquid. ¹H NMR (400 MHz, CDCl₃): δ = 9.98 (s, 1 H), 7.88–7.77 (m, 2 H), 7.61–7.48 (m, 2 H), 1.36 (s, 9 H) ppm. ¹³C NMR (100 MHz, CDCl₃): δ = 192.05 (CH), 158.53 (C), 134.30 (C), 129.84 (CH), 126.13 (CH), 35.49 (C), 31.23 (CH₃) ppm.

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