Yb(OTf)3-Catalyzed [4+2] Cycloaddition of Allenyltrimethylsilylthioketenes with Arylaldimines

Shigenobu Aoyagi; Satoru Ohata; Kazuaki Shimada; Yuji Takikawa

doi:10.1055/s-2007-970748

LETTER

Yb(OTf)₃-Catalyzed [4+2] Cycloaddition of Allenyltrimethylsilylthioketenes with Arylaldimines

Shigenobu Aoyagi*, Satoru Ohata, Kazuaki Shimada, Yuji Takikawa
Department of Chemical Engineering, Faculty of Engineering, Iwate University, 4-3-5 Ueda, Morioka, Iwate 0208551, Japan
Fax: +81(19)6216324; e-Mail: aoyagi@iwate-u.ac.jp;

Abstract

All articles of this category

Abstract

Yb(OTf)₃-catalyzed [4+2] cycloaddition of an in situ generated allenyltrimethylsilylthioketene with arylaldimines afforded unsaturated δ-thiolactams, one of which was converted into a known 4-azafluorenone, a synthetic precursor of onychine, in three steps.

Key words

allenyltrimethylsilylthioketene - arylaldimine - [4+2] cycloaddition - Yb(OTf)₃ - onychine

Full Text

References

References and Notes

<A NAME="RU14606ST-1A">1a</A> Barluenga J. Mateos C. Aznar F. Valdés C. J. Org. Chem. 2004, 69: 7114

<A NAME="RU14606ST-1B">1b</A> Mancheño OG. Arrayás RG. Carretero JC. J. Am. Chem. Soc. 2004, 126: 456

<A NAME="RU14606ST-1C">1c</A> Barluenga J. Mateos C. Aznar F. Valdés C. Org. Lett. 2002, 4: 1971

<A NAME="RU14606ST-1D">1d</A> Furman B. Dziedzic M. Tetrahedron Lett. 2003, 44: 6629

<A NAME="RU14606ST-2A">2a</A> Hattori K. Yamamoto H. J. Org. Chem. 1992, 57: 3264

<A NAME="RU14606ST-2B">2b</A> Ishihara K. Miyata M. Hattori K. Tada T. Yamamoto H. J. Am. Chem. Soc. 1994, 116: 10520

<A NAME="RU14606ST-2C">2c</A> Kobayashi S. Ishitani H. Nagayama S. Synthesis 1995, 1195

<A NAME="RU14606ST-2D">2d</A> Kobayashi S. Komiyama S. Ishitani H. Angew. Chem. Int. Ed. 1998, 37: 979

<A NAME="RU14606ST-2E">2e</A> Kobayashi S. Ishitani H. Chem. Rev. 1999, 99: 1069

<A NAME="RU14606ST-3">3</A> Bennett B. Okamoto I. Danheiser L. Org. Lett. 1999, 1: 641

<A NAME="RU14606ST-4A">4a</A> Shimada K. Akimoto S. Itoh H. Nakamura H. Takikawa Y. Chem. Lett. 1994, 1743

<A NAME="RU14606ST-4B">4b</A> Shimada K. Akimoto S. Takikawa Y. Kabuto C. Chem. Lett. 1994, 2286

<A NAME="RU14606ST-4C">4c</A> Koketsu M. Kanoh M. Itoh E. Ishihara H. J. Org. Chem. 2001, 66: 4099

<A NAME="RU14606ST-4D">4d</A> Koketsu M. Kanoh M. Yamamura Y. Ishihara H. Tetrahedron Lett. 2005, 46: 1479

<A NAME="RU14606ST-4E">4e</A> Aoyagi S. Sugimura K. Kanno N. Watanabe D. Shimada K. Takikawa Y. Chem. Lett. 2006, 992

<A NAME="RU14606ST-5">5</A> Aoyagi S. Hakoishi M. Suzuki M. Nakanoya Y. Shimada K. Takikawa Y. Tetrahedron Lett. 2006, 47: 7763

<A NAME="RU14606ST-6A">6a</A> de Almeida MEI. Braz FR. von Bulow MV. Gottleib OR. Maia JGS. Phytochemistry 1976, 15: 1186

<A NAME="RU14606ST-6B">6b</A> Goulart MOF. Santana AEG. de Oliveira AB. de Oliveira GG. Maia JGS. Phytochemistry 1986, 25: 1691

<A NAME="RU14606ST-6C">6c</A> Arango GJ. Cortes D. Cassels BK. Cave A. Merienne C. Phytochemistry 1987, 26: 2093

<A NAME="RU14606ST-6D">6d</A> Tadic D. Cassels BK. Cave A. Goulart MPF. de Oliveira AB. Phytochemistry 1987, 26: 1551

<A NAME="RU14606ST-6E">6e</A> Tadic D. Cassels BK. Cave A. Heterocycles 1988, 27: 407

<A NAME="RU14606ST-7A">7a</A> Koyama J. Sugita T. Suzuta Y. Irie H. Heterocycles 1979, 12: 1017

<A NAME="RU14606ST-7B">7b</A> Zhang J. El-Shabrawy O. El-Shabrawy MA. Schiff PL. Slatkin DJ. J. Nat. Prod. 1987, 50: 800

<A NAME="RU14606ST-7C">7c</A> Alves T. de Oliveira AB. Snieckus V. Tetrahedron Lett. 1988, 29: 2135

<A NAME="RU14606ST-7D">7d</A> Koyama J. Okatani T. Tagahara K. Heterocycles 1989, 29: 1648

<A NAME="RU14606ST-7E">7e</A> Bracher F. Synlett 1991, 95

<A NAME="RU14606ST-7F">7f</A> Nitta M. Ohnuma M. Iino Y. J. Chem. Soc., Perkin Trans. 1 1991, 1115

<A NAME="RU14606ST-7G">7g</A> Padwa A. Heidelbaugh TM. Kuethe JT. J. Org. Chem. 2000, 65: 2368

A CHCl₃ (30 mL) solution of 1a (900 mg, 4.95 mmol), N-(p-methoxybenzyl)-2-bromobenzylidenamine (3f; 100 mg, 3.29 mmol) and Yb(OTf)₃ (408 mg, 0.66 mmol) was heated to reflux for 14 h. The resulting reaction mixture was subjected to column chromatography on silica gel (hexane-EtOAc, 10:1). 4f: yield: 1040 mg (65%); yellow plates; mp 138.8-139.2 °C. MS: m/z (%) = 485 (6) [M⁺], 470 (47) [M⁺ - Me], 412 (16) [M⁺ - TMS], 121 (100) [PMB]. IR (KBr): 2943, 1514, 1514, 1475, 1253, 1244, 875, 844 cm^-1. ¹H NMR (400 MHz, CDCl₃): δ = 0.45 (s, 9 H), 1.93 (s, 3 H), 3.78 (s, 3 H), 3.99 (d, J = 14.5 Hz, 1 H), 5.34 (s, 1 H), 5.61 (s, 1 H), 5.67 (s, 1 H), 8.08 (d, J = 14.5 Hz, 1 H), 6.81 (d, J = 8.6 Hz, 2 H), 7.10-7.15 (m, 1 H), 7.21-7.25 (m, 2 H), 7.28 (d, J = 8.6 Hz, 2 H), 7.52 (d, J = 7.9 Hz, 1 H). ¹³C NMR (100 MHz, CDCl₃): δ = 3.2 (q), 19.0 (q), 54.0 (t), 55.2 (q), 62.6 (d), 113.9 (d), 117.5 (dd), 123.1 (s), 127.5 (d), 127.8 (d), 128.1 (s), 129.5 (d), 129.7 (d), 133.6 (d), 136.6 (s), 141.4 (s), 141.9 (s), 142.7 (s), 159.1 (s), 195.6 (s). Anal. Calcd for C₂₄H₂₈BrNOSSi: C, 59.25; H, 5.80; N, 2.88. Found: C, 59.14; H, 5.89; N, 2.90.

<A NAME="RU14606ST-9">9</A> Kochhar KS. Cottrell DA. Pinnick HW. Tetrahedron Lett. 1983, 24: 1323

<A NAME="RU14606ST-10A">10a</A> Davis FA. Jenkins R. Yochlovich SG. Tetrahedron Lett. 1978, 5171

<A NAME="RU14606ST-10B">10b</A> Davis FA. Awad SB. Jenkins RH. Billmers RL. Jenkins LA. J. Org. Chem. 1983, 48: 3071

To a CHCl₃ (30 mL) solution of 4f (500 mg, 1.03 mmol) was added N-tosyl-3-phenyloxaziridine (340 mg, 1.23 mmol) portionwise at 0 °C and then the solution was stirred at r.t. for 30 min. The reaction was quenched with an excess amount of aq Na₂SO₃ solution and the organic layer was separated and dried over anhyd Na₂SO₄. After evaporation of the solvent, the residue was subjected to column chromatography on silica gel (hexane-EtOAc = 7:1). 6f: yield: 325 mg (67%); colorless oil. MS: m/z (%) = 469 (19) [M⁺], 454 (19) [M⁺ - Me], 121 (100) [PMB]. IR (neat): 2951, 1625, 1512, 1247, 1036, 845 cm^-1. ¹H NMR (400 MHz, CDCl₃): δ = 0.39 (s, 9 H), 1.99 (s, 3 H), 3.47 (d, J = 14.6 Hz, 1 H), 3.78 (s, 3 H), 5.22 (d, J = 14.6 Hz, 1 H), 5.28 (s, 1 H), 5.55 (s, 1 H), 5.59 (s, 1 H), 6.81 (d, J = 6.6 Hz, 2 H), 7.10-7.20 (m, 1 H), 7.22 (d, J = 6.6 Hz, 2 H), 7.24-7.29 (m, 2 m), 7.53-7.55 (m, 1 H). ¹³C NMR (100 MHz, CDCl₃): δ = 2.0 (q), 18.6 (q), 47.0(dd), 55.1 (q), 61.1 (d), 113.6 (d), 115.7 (dd), 122.8 (s), 127.6 (d), 127.8 (d), 129.3 (s), 129.8 (d), 133.3 (d), 134.0 (s), 139.3 (s), 142.9 (s), 150.4 (s), 158.8 (s), 166.6 (s). Anal. Calcd for C₂₄H₂₈BrNO₂Si: C, 61.27; H, 6.00; N, 2.98. Found: C, 61.09; H, 6.07; N, 2.97.

A DMF solution (10 mL) of 6f (300 mg, 64 mmol), tri(o-tolyl)phosphine (19 mg, 6 mmol), Pd(OAc)₂ (7 mg, 3 mmol) and Et₃N (323 mg, 320 mmol) was stirred at 90 °C for 12 h under a N₂ atmosphere. After removal of DMF by distillation under reduced pressure, the residue was subjected to column chromatography on silica gel (hexane-EtOAc, 7:1). 7f: yield: 144 mg (58%); pale yellow plates; mp 142.7-144.0 °C. MS: m/z (%) = 389 (42) [M⁺], 374 (23) [M⁺ - Me], 121 (100) [PMB]. IR (KBr): 2951, 1619, 1579, 1247, 850 cm^-1. ¹H NMR (400 MHz, CDCl₃): δ = 0.39 (s, 9 H), 2.40 (s, 3 H), 3.62 (s, 2 H), 3.73 (s, 3 H), 5.66 (br s, 2 H), 6.80 (d, J = 8.2 Hz, 2 H), 7.09 (d, J = 8.2 Hz, 2 H), 7.21 (t, J = 7.6 Hz, 1 H), 7.28 (t, J = 7.4 Hz, 1 H), 7.51 (d, J = 7.4 Hz, 1 H), 7.58 (d, J = 7.9 Hz, 1 H). ¹³C NMR (100 MHz, CDCl₃): δ = 1.7 (q), 19.7 (q), 34.4 (t), 46.6 (t), 55.1 (q), 114.1 (d), 122.4 (s), 122.5 (d), 124.5 (d), 125.1 (d), 126.95 (d), 127.01 (d), 127.4 (d), 128.4 (s), 136.4 (s), 144.0 (s), 146.1 (s), 153.6 (s), 158.5 (s), 166.4 (s). Anal. Calcd for C₂₄H₂₇NO₂Si: C, 74.00; H, 6.99; N, 3.60. Found: C, 73.83; H, 7.15; N, 3.65.

A CHCl₃ (30 mL) solution of 7f (120 mg, 31 mmol) and p-toluenesulfonic acid monohydrate (205 mg, 108 mmol) was heated to reflux for 5 h. The reaction was quenched with an excess amount of aq NaHCO₃ solution and the organic layer was separated and dried over anhyd Na₂SO₄. After evaporation of the solvent, the residue was subjected to column chromatography on silica gel (hexane-EtOAc = 7:1). 8f: yield: 86 mg (88%); pale yellow solid; mp 162.2-163.8 °C (lit. [7g] 164-165 °C). MS: m/z (%) = 317 (10) [M⁺], 121 (100) [PMB]. IR (KBr): 2956, 1651, 1526, 1516, 1252, 1174, 1032, 842 cm^-1. ¹H NMR (400 MHz, CDCl₃): δ = 2.32 (s, 3 H), 3.62 (s, 2 H), 3.73 (s, 3 H), 5.71 (br s, 2 H), 6.48 (s, 1 H), 6.82 (d, J = 8.6 Hz, 2 H), 7.12 (d, J = 8.6 Hz, 2 H), 7.25-7.35 (m, 2 H), 7.54 (d, J = 7.1 Hz, 1 H), 7.62 (d, J = 7.6 Hz, 1 H). ¹³C NMR (100 MHz, CDCl₃): δ = 19.0 (q), 33.6 (t), 46.8 (t), 55.2 (q), 114.2 (d), 116.6 (d), 121.9 (s), 122.5 (d), 125.2 (d), 127.07 (d), 127.13 (d), 127.4 (d), 128.2 (s), 136.3 (s), 144.4 (s), 145.6 (s), 147.5 (s), 158.6 (s), 163.7 (s).