Chelation-Based Homologation by Reaction of Organometallic Reagents with O-Alkyl S-Pyridin-2-yl Thiocarbonates: Synthesis of Esters from Grignard Reagents

This paper is dedicated to the memory of Professor Teruaki Mukaiyama, a prominent scientist who made major contributions to the field.

Abstract

The one-carbon homologative esterification of Grignard reagents with O-alkyl S-pyridin-2-yl thiocarbonates has been explored. This one-step synthesis of esters from Grignard reagents is the first case to involve chelation-stabilized intermediates.

Key words

alkyl pyridinyl thiocarbonates - Grignard reagents - esterification - one-step synthesis - homologation

• References and Notes

• 1a March’s Advanced Organic Chemistry: Reactions, Mechanism, and Structure (6th ed.). Smith MB, March J. Wiley-Interscience; Hoboken: 2007. Chap. 16 1445
• 1b Moyer WW, Marvel CS. Org. Synth. Col. Vol II . Wiley; London: 1931: 602

A dry carbon dioxide equivalent of the Grignard reaction has recently been reported; see:
• 2a Inagaki F, Matsumoto C, Iwata T, Mukai C. J. Am. Chem. Soc. 2017; 139: 4639

More recently, sodium methyl carbonate was found to react with Grignard reagents to afford carboxylic acids; see:
• 2b Hurst TE, Deichert JA, Kapeniak L, Lee R, Harris J, Jessop PG, Snieckus V. Org. Lett. 2019; 21: 3882
• 3 Maeda H, Takahashi K, Ohmori H. Tetrahedron 1998; 54: 12233
• 4 Kashima C, Tsuruoka S, Mizuhara S. Tetrahedron 1998; 54: 14679
• 5 Werner T, Barrett AG. M. J. Org. Chem. 2006; 71: 4302
• 6 For Grignard reagent complexes chelated with TDA-1, see: Boudin A, Cerveau G, Chuit C, Corriu RJ. P, Reye C. Tetrahedron 1989; 45: 171
• 7 Bottalico D, Fiandanese V, Marchese G, Punzi A. Synlett 2007; 974
• 8 For Mukaiyama’s 2-pyridyl thioesters, see: Mukaiyama T, Araki M, Takei H. J. Am. Chem. Soc. 1973; 95: 4763

For Weinreb amides, see:
• 9a Nahm S, Weinreb SM. Tetrahedron Lett. 1981; 22: 3815

For a review of the synthetic utility of Weinreb amides, see:
• 9b Balasubramaniam S, Aidhen IS. Synthesis 2008; 3707
• 10 The use of dialkyl alkoxycarbonylphosphonates might be classified into this category: see ref. 3.
• 11a Kim S, Lee JI, Yi KY. Bull. Chem. Soc. Jpn. 1985; 58: 3570
• 11b Lee JI, Jung HJ. J. Korean Chem. Soc. 2005; 49: 609
• 12 Compound 3 was originally prepared in two steps by the reaction of phosgene with pyridine-2-thiol to give S,S-di-2-pyridyl dithiocarbonate, followed by treatment with Cu(O ^t Bu)₂.^11a The present method provides an operationally simple one-step synthesis.
• 13 Benzyl Benzoate (4a); Typical Procedure A 1.0 M solution of PhMgBr (5a) in THF (98 mL, 98 mmol) was added to a stirred solution of 1 (24.1 mg, 98.2 μmol) in dry THF (1.0 mL) at 0 °C and the mixture was kept at 50 °C for 1 h, then cooled to 0 °C. An aqueous solution of NH₄Cl was added, and the mixture was extracted with Et₂O. The organic layer was washed with brine, dried (Na₂SO₄), and concentrated in vacuo. The residue purified by chromatography [silica gel, hexane–EtOAc (20:1)] to give 4a as an oil; yield: 17.5 mg (84%). ¹H NMR (300 MHz, CDCl₃): δ = 8.10–8.06 (m, 2H), 7.32–7.59 (m, 8 H), 5.37 (s, 2 H). This spectrum was identical with that reported.¹⁴
• 14 Li L, Sheng H, Xu F, Shen Q. Chin. J. Chem. 2009; 27: 1127