Synthesis of 5-(2-methoxy-1-naphthyl)- and 5-[2-(methoxymethyl)-1-naphthyl]-11H-benzo[b]fluorene as 2,2'-disubstituted 1,1'-binaphthyls via benzannulated enyne–allenes

• Yu-Hsuan Wang,
• Joshua F. Bailey,
• Jeffrey L. Petersen and
• Kung K. Wang

Beilstein J. Org. Chem. 2011, 7, 496–502, doi:10.3762/bjoc.7.58

• synthesized by treatment of the corresponding benzannulated enediynes with potassium tert-butoxide in refluxing toluene to give benzannulated enyne–allenes for the subsequent Schmittel cascade cyclization reactions. The structures of these two 5-(1-naphthyl)-11H-benzo[b]fluorenes could be regarded as 2,2

• '-disubstituted 1,1'-binaphthyls with the newly constructed benzofluorenyl group serving as a naphthyl moiety. Keywords: benzannulated enediynyl alcohols; benzannulated enyne–allenes; 2,2'-disubstituted 1,1'-binaphthyls; 5-(1-naphthyl)-11H-benzo[b]fluorenes; Schmittel cascade cyclizations; Introduction

• Benzannulated enyne–allenes bearing an aryl substituent at the alkynyl terminus are excellent precursors of 5-aryl-11H-benzo[b]fluorenes [1][2][3][4][5]. Several synthetic pathways to the benzannulated enyne–allene systems have been reported, including generation in situ from the corresponding benzannulated