第一章部份，我們報導了一種新的三氟甲磺酸氧釩VO(OTf)2催化系統，當應用於醛和酮類化合物的硫縮醛化反應 (thioacetalization)，以及縮醛類化合物 (acetals) 的交換硫縮醛化反應 (transthioacetalization) 時，對於羰官能基有很高的化學選擇性，例如醛基相對於酮基、烯酮基相對於酮基等；而且與羥基 (hydroxy)、烷氧基 (alkoxy)、醯氧基 (acyloxy)、鹵化物 (halide)、胺基 (amino)、硝基 (nitro)、酸 (acid) 和酯 (ester) 等官能基，亦俱備了多元化的相容性。除了反應可在室溫下溫和地進行外，VO(OTf)2催化劑用量大都小於10 mol%，而且可以直接使用硫醇 (thiols) 或二硫醇 (dithiols) 當作親核劑反應物，這些結果均優於一般常用的布忍斯特酸 (Brønsted acids) 或路易斯酸 (Lewis acids) 催化劑，這也揭示了對於有機合成化學將有很大的應用性與實用性。此外，苯甲醛的二硫縮醛化合物的去保護基研究，經運用我們的Ac2O/VO(OTf)2催化系統在無溶劑條件下，可直接轉換為苯甲醛的二乙酸酯 (diacetate，acylal) 化合物，亦是另一項有趣的結果。
第二章部份，我們首次報導了使用三氟甲磺酸氧釩VO(OTf)2催化劑，來促進(hetero)Michael addition反應，以形成C-X和C-C鍵的成功範例。反應性較大的含硫親核劑，進行thia-Michael addition時可獲得很高的產率，而且與羥基 (hydroxy)、烷氧基 (alkoxy)、鹵化物 (halide)、嘧啶基 (pyrimidyl) 等官能基均有很好的相容性。反應性較弱的含氧、含氮親核劑，例如醇 (alcohols)、醯胺 (amides) 和磺酸鹽 (sulfonates) 等，亦可直接進行oxa-及aza-Michael addition反應。此外，氫膦化合物 (hydrogen phosphines) 和氫亞磷酸鹽 (hydrogen phosphites) 等含磷親核劑，在VO(OTf)2催化下亦能成為很有用的phospha-Michael addition的Michael donor；其中全新發展出來的同步、自動 (in situ) 生成的乙醯亞磷酸鹽 (acetylphosphite)，經過VO(OTf)2催化劑活化後，可與α,β-烯酮化合物 (α,β-enones) 進行共軛加成反應。最後，在相同催化條件下，各種富含電子的 (雜環)芳族烴和α,β-不飽和羰基化合物，亦均能有效地進行Friedel- Crafts-type conjugate addition以形成碳－碳鍵，而且其反應步驟非常簡單、易操作。

In the first part, a series of thiols and dithiols has been examined as protic nucleophiles for double nucleophilic condensations with aldehydes, ketones, and acetals catalyzed by amphoteric, water-tolerant vanadyl triflate under mild and neutral conditions. A preliminary study for catalytical acylative dethioacetalization in neat acetic anhydride has also been examined. The newly developed C-S bond formation and scission protocols were carried out smoothly in good to high yields in a highly chemoselective manner.
In the second part, a series of thiols, alcohols, carbamates, amides, N-tosyl amides, hydrogen phosphines/phosphites, and (hetero)arenes has been examined as nucleophiles for (hetero)Michael-type additions to enones and enamides catalyzed by amphoteric vanadyl triflate under mild and neutral conditions. The newly developed C-S, C-O, C-N, C-P, and C-C bond formation protocols were carried out smoothly in good to high yields without intervention of any 1,2-additions.

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(26) The chemical yields are around 34-50% when the reactions were performed at ambient temperature in neat benzamide.
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(28) For reviews, see: (a) Pudovik, A. N.; Konovalova, I. V. Synthesis 1979, 81. (b) Wozniak, L.; Chojnowski, J. Tetrahedron 1989, 45, 2465. (c) Kolodiazhnyi, O. I. Tetrahedron: Asymmetry 1998, 9, 1279. (d) Baillie, C.; Xiao, J. Curr. Org. Chem. 2003, 7, 477. (e) Tanaka, M. Top. Curr. Chem. 2004, 232, 25. (f) Kolodiazhnyi, O. I. Tetrahedron: Asymmetry 2005, 16, 3295. (g) Enders, D.; Saint-Dizier, A.; Lannou, M.-I.; Lenzen, A. Eur. J. Org. Chem. 2006, 29. (h) Troev, K. D. Chemistry and Application of H-Phosphonates; Elsevier: Amsterdam, 2006.
(29) (a) Evans, D. A.; Hurst, K. M.; Takacs, J. M. J. Am. Chem. Soc. 1978, 100, 3467. (b) Liotta, D.; Sunay, U.; Ginsberg, S. J. Org. Chem. 1982, 47, 2227. (c) Mori, I.; Kimura, Y.; Nakano, T.; Matsunaga, S.-I.; Iwasaki, G.; Ogawa, A.; Hayakawa, K. Tetrahedron Lett. 1997, 38, 3543.
(30) Overall, 1 equiv of Ac2O is needed in the acetylation of hydrogen phosphite and 1 equiv of HOAc (the byproduct in the acetylation step) is needed for the protonation of II.
(31) About 15-20% yields of the addition products 23h and 23j were isolated without the addition of vanadyl triflate at 70 °C for 48 h.
(32) For reviews, see: (a) Olah, G. A.; Kishnamurti, R.; Prakash, G. K. S. In Comprehensive Organic Synthesis; Trost, B. M., Fleming, I., Ed.; Pergamon Press: Oxford, 1991; Vol. 3, pp 293-339. (b) Jørgensen, K. A. Synthesis 2003, 1117. (c) Bandini, M.; Melloni, A.; Umani-Ronchi, A. Angew. Chem. Int. Ed. 2004, 43, 550.
(33) (a) Sundberg, R. J. The Chemistry of Indoles; Academic Press: New York, 1970. (b) Gilchrist, T. L. Heterocyclic Chemistry; 3rd ed.; Addison Wesley Longman: Essex, 1997.