Atom-Transfer Cyclization with CuSO4/KBH4: A Formal 鈥淎ctivators Generated by Electron Transfer鈥?Process Also Applicable to Atom-Transfer Polymerization

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• 作者：Andrew J. Clark ; Alana E. C. Collis ; David J. Fox ; Lauren L. Halliwell ; Natalie James ; Rachel K. O鈥橰eilly ; Hemal Parekh ; Andrew Ross ; Andrew B. Sellars ; Helen Willcock ; Paul Wilson
• 刊名：The Journal of Organic Chemistry
• 出版年：2012
• 出版时间：August 17, 2012
• 年：2012
• 卷：77
• 期：16
• 页码：6778-6788
• 全文大小：436K
• 年卷期：v.77,no.16(August 17, 2012)
• ISSN：1520-6904

文摘

The 4-exo and 5-exo-trig atom-transfer cyclizations of 1, 8a鈥?b>e, 9, 12, and 13 can be mediated with as little as 0.05 mol % of Cu(TPMA)SO₄路5H₂O in the presence of 2.5 mol % of borohydride salts in 10 min at room temperature in air. This formal 鈥渁ctivators generated by electron transfer鈥?(AGET) procedure utilizes a cheap and oxidatively stable copper source (CuSO₄路5H₂O) and can be carried out in environmentally benign solvents (EtOH). It is possible to alter the product distribution in the 5-endo radical鈥損olar crossover reactions of 10a,b and 11 by tailoring the amount of borohydride. Cyclization onto alkynes 14 and 15 is also possible in only 20 min. Controlled radical polymerization of styrene, with increased rates over conventional atom-transfer radical polymerization (ATRP), can be carried out in a controlled fashion (Mn, PDI) using either CuBr or CuSO₄路5H₂O and Bu₄NBH₄.