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2 Regioselective synthesis of 2-(arylthio)benzoates by the first [3+3] cyclizations of 3-arylthio-1-silyloxy-1,3-butadienes with 3- alkoxy-2-en-1-ones 2.1 Introduction The synthesis of methyl 4,6-dimethyl-2-(phenoxythio)benzoate by cyclization of 1- methoxy-1-trimethylsilyloxy-3-phenoxythio-1,3-butadiene with 4- (trimethylsilyloxy)pent-3-en-2-one has also been reported. 23 Recently, I have studied the synthesis of 2-arylthio-5-(haloethyl)benzoates by cyclization of 3-arylthio-1- silyloxy-1,3-butadienes with 1,1-diacylcyclopropanes. 26 Herein I report what are, to the best of my knowledge, the first [3+3] cyclizations of 3-arylthio-1-silyloxy-1,3- butadienes with 3-alkoxy-2-en-1-ones. These reactions provide a convenient and regioselective approach to sterically encumbered and functionalized 2- (arylthio)benzoates which are not readily available by other methods. In contrast to the coupling reactions outlined above, my method relies on the assembly of one of the two arene moieties. 2.2 Result and discussions The TiCl4-mediated cyclization of 3-phenoxythio-1-silyloxy-1,3-butadiene 3a with 1- (methoxy)but-1-en-3-one (11a) afforded methyl 6-methyl-2-(phenoxythio)benzoate (12a) with very good regioselectivity (Scheme 11). Notably, the formation of regioisomeric methyl 4-methyl-2-(phenoxythio)benzoate was not observed. The best yields were obtained when the reaction was carried out in a highly concentrated 28
solution. The use of an excess (1.5 equiv.) of 4a and of TiCl4 also proved to be important. The formation of 5a can be explained by TiCl4-mediated conjugate addition of the terminal carbon atom of 3a onto 11a to give intermediate A, cyclization via the central carbon atom (intermediate B), (Scheme 10), and subsequent aromatization. PhS OSiMe 3 OMe O 3a OMe OMe Me i Me 11a 12a (53%) PhS TiCl 4 Me 3SiCl O O A OMe TiCl 3OMe Me TiCl 2(OH)OMe HCl 29 SPh SPh O B O OMe OTiCl2OMe Scheme 10. Possible mechanism of the formation of 12a; conditions: i: 1) TiCl4, CH2Cl2, −78 to 20 °C, 20 h; 2) NaHCO3, H2O Me
Page 1 and 2: Synthesis of functionalized 2-(aryl
Page 3 and 4: The ink of the scholar is more holy
Page 5 and 6: Affectionately Dedicated to “All
Page 7 and 8: Table of Contents 03 List of used a
Page 9 and 10: RCM Ring Closing Metathesis TBAI Te
Page 11 and 12: humans: 1) the thiomethyl of methio
Page 13 and 14: Chart 3. Structure of sumatriptan S
Page 15 and 16: disulfide (DADS) and diallyl sulfid
Page 17 and 18: 1. Synthesis of functionalized 2-(a
Page 19 and 20: 3-Arylthio-1-trimethylsilyloxy-1,3-
Page 21 and 22: under kinetic reaction control, by
Page 23 and 24: l a u 4-FC6H4 H Me H 40 m a v 4-FC6
Page 25 and 26: Table 2. Synthesis of thioxanthones
Page 27 and 28: 3a O OSiMe 3 O OMe + Me Me Cl 3TiO
Page 29 and 30: Table 3. Synthesis of 8a-x 3 7 8 Ar
Page 31: Cl + SPh OSiMe 3 3a 9 O OMe O O H i
Page 35 and 36: Table 4. Synthesis of 12a-r 3 11 12
Page 37 and 38: 2.3 Conclusion In conclusion, I hav
Page 39 and 40: aromatization). An unseparable 1:2
Page 41 and 42: Table 5. Synthesis of arenes 14a-l
Page 43 and 44: 3.3 Conclusion In conclusion, I hav
Page 45 and 46: Mass Spectroscopy: AMD MS40, AMD 40
Page 47 and 48: 131.0 (ArCH), 132.7, 134.0, 135.9,
Page 49 and 50: (EI, 70 eV): m/z (%): 380 (100), 21
Page 51 and 52: (m), 1490 (m), 1434 (m), 1383 (w),
Page 53 and 54: 15.4, 16.9, 18.9 (CH3), 28.3 (CH2),
Page 55 and 56: (C). IR (neat): ν̃ = 2945 (w), 29
Page 57 and 58: 948 (w) 853 (m), 803 (m), 751 (m),
Page 59 and 60: 135.4, 139.2, 143.8, 146.5, 182.2 (
Page 61 and 62: Me S O Me Ph Br Methyl 4-methyl-5-(
Page 63 and 64: 35 Cl, 37 Cl, 61), 430 (M + , 35 Cl
Page 65 and 66: ArH). 13 C NMR (62 MHz, CDCl3): δ
Page 67 and 68: Me S O Me Me Methyl 4,6-dimethyl-5-
Page 69 and 70: S Methyl 4-methyl-5-(2-bromoethyl)-
Page 71 and 72: (CH2CH3), 33.3 (CH2), 40.1 (CH2), 5
Page 73 and 74: Me 3,4-Dimethyl-2-phenylsulfanyl-be
Page 75 and 76: Me 3,4-Dimethyl-2-(p-tolylsulfanyl)
Page 77 and 78: OCH3), 7.08-7.17 (m, 7H, Ar); 13 C
Page 79 and 80: (w), 750 (s), 732 (s), 688 (s), 650
Page 81 and 82: 35 Cl 35 Cl, 100), 359 (26), 357 (3
Page 83 and 84:
2924 (w), 2853 (w), 1728 (s), 1712
Page 85 and 86:
Me 3-Hydroxy-5-(4-methylphenylsulfa
Page 87 and 88:
Et 3-Hydroxy-5-(4-ethylphenylsulfan
Page 89 and 90:
(13), 264 (13), 262 (36) ,260 (12),
Page 91 and 92:
MS (EI, 70 eV): m/z (%) = 337 (16),
Page 93 and 94:
OH O 5'-Hydroxy-[1,1';3',1'']terphe
Page 95 and 96:
Refrences 1. Handbook of Chemistry
Page 97 and 98:
20. For a review of [3+3] cyclizati
Page 99 and 100:
Nationality Pakistan Place of Birth
Page 101 and 102:
Publications 1. Inam Iqbal, Muhamma
Page 103 and 104:
Tetrahedron 2007, 63, 12562-12575.
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List of used abbreviations - RosDok - Universität Rostock

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