Synlett, Table of Contents Synlett 2021; 32(05): 521-524DOI: 10.1055/s-0040-1707161 cluster The Power of Transition Metals: An Unending Well-Spring of New Reactivity © Georg Thieme Verlag Stuttgart · New YorkZinc-Catalyzed Transacetalization of N,O-Acetals into N,N-Acetals with Benzotriazoles, Indazoles, and Azides Authors Author Affiliations Sang Ik Shin Nguyen H. Nguyen Jangbin Im Seunghoon Shin ∗ Department of Chemistry, Center for New Directions in Organic Synthesis (CNOS) and Research Institute for Natural Sciences, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul 04763, Korea Email: sshin@hanyang.ac.kr Recommend Article Abstract Buy Article(opens in new window) All articles of this category(opens in new window) This paper is dedicated to Professor Barry M. Trost to celebrate his career on the occasion of 20 years of Science of Synthesis. Abstract N,O-Acetals obtained from β-oxidation of ynamides underwent transacetalization with benzotriazoles, leading to N,N-acetals. The Zn(OTf)2 efficiently catalyzed the process, and the reaction is further accelerated in hexafluoroisopropanol, providing a single N1-regiosiomer. The transacetalization conditions developed could be extended to other N-donors, such as 1H-indazole and TMSN3 to afford the corresponding N,N-acetals. Key words Key wordsZn catalysis - transacetalization - N,N-acetal - ynamide - benzotriazole Full Text References References and Notes 1a Ren Y, Zhang L, Zhou C. -H, Geng R. -X. Med. Chem. 2014; 4: 640 1b Suma BV, Natesh NN, Madhavan V. J. Chem. Pharm. Res. 2011; 3: 375 2a Xu K, Thieme N, Breit B. Angew. Chem. Int. Ed. 2014; 53: 7268 2b Chen S.-W, Zhang G.-C, Lou Q.-X, Cui W, Zhang S.-S, Hu W.-H, Zhao J.-L. ChemCatChem 2015; 7: 1935 2c Duan H, Yan W, Sengupta S, Shi X. Bioorg. Med. Chem. Lett. 2009; 19: 3899 2d Yan W, Ye X, Weise K, Petersen JL, Shi X. Chem. Commun. 2012; 48: 3521 3 Wang K, Chen P, Ji D, Zhang X, Xu G, Sun J. Angew. Chem. Int. Ed. 2018; 57: 12489 4a Katritzky AR, Chang H.-X, Wu J. Synthesis 1994; 907 4b Niedermann K, Früh N, Senn R, Czarnieckim B, Verel R, Togni A. Angew. Chem. Int. Ed. 2012; 51: 6511 4c Yan W, Wang Q, Chen Y, Petersen JL, Shi X. Org. Lett. 2010; 12: 3308 5a Wu J, Zhou Y, Zhou Y, Chiang C.-W, Lei A. ACS Catal. 2017; 7: 8320 5b Aruri H, Singh U, Sharma S, Gudup S, Bhogal M, Kumar S, Singh D, Gupta VK, Kant R, Wishwakarma RA, Singh PP. J. Org. Chem. 2015; 80: 1929 6a Liu Y, Yan W, Chen Y, Petersen JL, Shi X. Org. Lett. 2008; 10: 5389 6b Lee H.-G, Won J.-E, Kim M.-J, Park S.-E, Jung K.-J, Kim BR, Lee S.-G, Yoon Y.-J. J. Org. Chem. 2009; 74: 5675 For reviews, see: 7a Yeom H.-S, Shin S. Acc. Chem. Res. 2014; 47: 966 7b Zhang L. Acc. Chem. Res. 2014; 47: 877 For selected examples, see: 7c Arava S, Kumar JN, Maksymenko S, Iron MA, Parida KN, Fristrup P, Szpilman AM. Angew. Chem. Int. Ed. 2017; 56: 2599 7d Li L, Shu C, Zhou B, Yu Y.-F, Xiao X.-Y, Ye LW. Chem. Sci. 2014; 5: 4057 7e Li L, Zhou B, Wang Y.-H, Shu C, Pan Y.-F, Lu X, Ye LW. Angew. Chem. Int. Ed. 2015; 54: 8245 7f Kaldre D, Maryasin B, Kaiser D, Gajsek O, González L, Maulide N. Angew. Chem. Int. Ed. 2017; 56: 2212 For Brønsted acid catalyzed approaches, see: 8a Patil DV, Shin S. Asian J. Org. Chem. 2019; 8: 63 8b Patil DV, Kim SW, Nguyen QH, Kim H, Wang S, Hoang T, Shin S. Angew. Chem. Int. Ed. 2017; 56: 3670 8c Kim SW, Um T.-W, Shin S. Chem. Commun. 2017; 53: 2733 8d Nguyen QH, Nguyen NH, Kim H, Shin S. Chem. Sci. 2019; 10: 8799 8e Um T.-W, Lee G, Shin S. Org. Lett. 2020; 22: 1985 For the Zn-catalyzed addition of N-hydroxybenzotriazoles, see: 8f Im J, Shin SI, Cho C.-G, Shin S. J. Org. Chem. 2020; 85: 6935 9 Nguyen NH, Nguyen QH, Biswas S, Patil DV, Shin S. Org. Lett. 2019; 21: 9009 10 Singh AS, Kumar D, Mishra N, Tiwari VK. ChemistrySelect 2017; 2: 224 11 Shao C, Wang X, Zhang Q, Luo S, Zhao J, Hu Y. J. Org. Chem. 2011; 76: 6832 12 Synthesis of 3 – Typical Procedure for 3a In a 4 mL vial, the N,O-acetal 1a (38.2 mg, 0.1 mmol), benzotriazole (2, 35.7 mg, 0.3 mmol), and Zn(OTf)2 (3.6 mg, 0.01 mmol) were dissolved in hexafluoroisopropanol (HFIP, 1 mL). The reaction mixture was then heated to 60 °C for 9 h, when the reaction was judged to be complete (TLC). The mixture was concentrated to dryness, and the residue was purified by SiO2 flash chromatography (EtOAc/n-hexane/CH2Cl2 = 1:15:5) to afford 3a (30 mg, 87%) as a white solid; mp 108–110 ℃. 1H NMR (400 MHz, CDCl3): δ = 8.11 (d, J = 9.2 Hz, 1 H), 7.92 (s, 1 H), 7.83 (d, J = 8.4 Hz, 1 H), 7.79 (d, J = 7.3 Hz, 2 H), 7.63 (t, J = 15.4 Hz, 1 H), 7.55 (t, J = 14.9 Hz, 1 H), 7,48 (t, J = 15.4 Hz, 1 H), 7.38 (t, J = 13.9 Hz, 2 H), 3.10 (s, 3 H), 2.94 (s, 3 H). 13C NMR (100 MHz, CDCl3): δ = 189.0, 145.8, 134.5, 133.5, 132.4, 129.1, 128.5, 125.0, 120.5, 109.7, 71.4, 38.9, 31.3. HRMS (EI): m/z [M]+ calcd for C16H16N4O3S+: 344.0938; found: 344.0941. Supplementary Material Supplementary Material Supporting Information (PDF) (opens in new window)
