A 1, 1‐Carboboration Route to Bora‐Nazarov Systems. Issue 11 (17th August 2015)

• Record Type: Journal Article
• Authors: Ge, Fang; Türkyilmaz, Fatma; Daniliuc, Constantin G.; Siedow, Melanie; Eckert, Hellmut; Kehr, Gerald; Erker, Gerhard
• Is Part Of: Chemistry, an Asian journal. Volume 10:Issue 11(2015:Nov.)
• Page Start: 2497
• Page End: 2502
• Publication Date: 2015-08-17
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1002/asia.201500636
• Languages: English
• ISSNs: 1861-4728

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>Hydroboration of the conjugated enynes <bold>1 a</bold> and <bold>1 b</bold> with Piers' borane [HB(C₆F₅)₂] gave the respective dienylboranes <italic>trans</italic>‐<bold>2 c</bold> and <italic>trans</italic>‐<bold>2 d</bold>. Their photolysis resulted in the formation of the dihydroborole products <bold>3 c</bold> and <bold>3 d</bold>. Both were converted to their pyridine adducts <bold>5 c</bold> and <bold>5 d</bold>, respectively. Compounds <bold>3 c</bold> and <bold>5 c, d</bold> were characterized by X‐ray diffraction. The reaction of the bis(enynyl)boranes <bold>6 a</bold> and <bold>6 b</bold> with B(C₆F₅)₃ resulted in the formation of the dihydroboroles <bold>7 a</bold> and <bold>7 b</bold>, respectively. This reaction is thought to proceed by 1, 1‐carboboration of one of the enynyl substituents at boron to generate the dienylborane intermediates <bold>8 a</bold>/<bold>8 b</bold>, followed by thermally induced bora‐Nazarov ring‐closure and subsequent stabilizing 1, 2‐pentafluorophenyl group migration from boron to carbon. Compound <bold>7 a</bold> was characterized by X‐ray diffraction and solid‐state ¹¹B NMR spectroscopy.</p> </abstract>