Rhodium-Catalyzed Addition of Arylboronic Acids to 2-Methylene-1,3-­dithiane Monoxide

Abstract

Treatment of 2-methylene-1,3-dithiane 1-oxide with arylboronic acid under rhodium catalysis in aqueous dioxane at 25 °C provided the corresponding adduct, which is a useful 2-aryl­alkanal equivalent.

rhodium - arylboronic acid - addition - methylene dithiane monoxide

References and Notes

<A NAME="RU02507ST-1A">1a</A> Kolb M. Synthesis  1990,  171 

<A NAME="RU02507ST-1B">1b</A> Yus M. Nájera C. Foubelo F. Tetrahedron  2003,  59:  6147 

<A NAME="RU02507ST-2">2</A> Yoshida S. Yorimitsu H. Oshima K. J. Organomet. Chem.  2007,  692:  in press ; doi: 10.1016/j.jorganchem.2006.12.029

Ketene dithioacetal monoxide is known as a Michael acceptor:

<A NAME="RU02507ST-3A">3a</A> Herrmann JL. Kieczykowski GR. Romanet RF. Wepplo PJ. Schlessinger RH. Tetrahedron Lett.  1973,  14:  4711 

<A NAME="RU02507ST-3B">3b</A> Nakane M. Hutchinson CR. J. Org. Chem.  1978,  43:  3922 

<A NAME="RU02507ST-4A">4a</A> Sakai M. Hayashi H. Miyaura N. Organometallics  1996,  16:  4229 

<A NAME="RU02507ST-4B">4b</A> Fagnou K. Lautens M. Chem. Rev.  2003,  103:  169 

<A NAME="RU02507ST-4C">4c</A> Hayashi T. Yamasaki K. Chem. Rev.  2003,  103:  2829 

<A NAME="RU02507ST-4D">4d</A> Yoshida K. Hayashi T. In Modern Rhodium-Catalyzed Organic Reactions   Evans PA. Wiley-VCH; Weinheim: 2005.  Chap. 3.

Addition to alkenylphosphonates:

<A NAME="RU02507ST-5A">5a</A> Hayashi T. Senda T. Takaya Y. Ogasawara M. J. Am. Chem. Soc.  1999,  121:  11591 

<A NAME="RU02507ST-5B">5b</A> Addition to nitroalkenes: Hayashi T. Senda T. Ogasawara M. J. Am. Chem. Soc.  2000,  122:  10716 

<A NAME="RU02507ST-6">6</A>

Experimental Procedure
The [Rh(OH)(cod)]₂ (7.3 mg, 0.016 mmol) was placed in a flask under an atmosphere of argon. A dioxane (3.0 mL) solution of 2-methylene-1,3-dithiane 1-oxide (1a, 44.1 mg, 0.30 mmol) and H₂O (0.3 mL) were added. Then, phenylboronic acid (2a, 43.8 mg, 0.36 mmol) was added, and the mixture was stirred at 25 °C for 3 h. The reaction mixture was poured into sat. aq NaHCO₃ (5 mL) and extracted with EtOAc (3 × 10 mL). The combined organic layer was dried over anhyd Na₂SO₄ and concentrated in vacuo. Purification by chromatography on a silica gel column provided 2-benzyl-1,3-dithiane 1-oxide (3a, 65.6 mg, 0.29 mmol, 97%).

<A NAME="RU02507ST-7">7</A> The product 3a is a known compound. The ¹H NMR and ¹³C NMR spectra of 3a were identical to the reported data: Page PCB. Wilkes RD. Namwindwa ES. Witty MJ. Tetrahedron  1996,  52:  2125 

<A NAME="RU02507ST-8">8</A>

The mechanism for the stereoselective formation of the cis-product 3a is not clear at this stage. Protonation of the intermediate shown in Figure [1] would be the key step.

<A NAME="RU02507ST-9">9</A>

The relative stereochemistry of 5 is not clear.

<A NAME="RU02507ST-10">10</A>

We are tempted to assume the stereochemistry of 6b based on the plausible reaction mechanism shown here (Scheme [6] ). Attempts to prepare X-ray-quality crystals of 6b or related compounds are in progress.

<A NAME="RU02507ST-11">11</A> Ogura K. Tsuchihashi G. Tetrahedron Lett.  1971,  34:  3151 

<A NAME="RU02507ST-12">12</A>

The relative stereochemistry of 8 has not been determined.

<A NAME="RU02507ST-13">13</A> Page PCB. Shuttleworth SJ. McKenzie MJ. Schilling MB. Tapolczay DJ. Synthesis  1995,  73