The syntheses of (+)-zincophorin methyl ester and graphene nanomaterials through redox-triggered coupling

(+)-Zincophorin methyl ester was prepared in 13 steps (LLS) representing a concise route to this iconic natural product. A bidirectional redox-triggered double anti-crotylation of 2-methyl-1,3-propane diol directly assembles the triketide stereopolyad spanning C4−C12, significantly enhancing step economy and enabling construction of (+)-zincophorin methyl ester in nearly half the steps previously required. A method for the ring expansion of cyclic diols is described. Using improved conditions for the ruthenium(0) catalyzed cycloaddition of cyclic 1,2-diols with 1,3-dienes, fused [n.4.0] bicycles (n = 3-6) are formed, which upon exposure to (diacetoxyiodo)benezene engage in oxidative cleavage to form 9–12 membered rings. Alternating ortho, para-oligophenylenes were prepared employing ruthenium catalyzed cycloaddition. Poly-ols prepared through dihydroxylation of vinyl-phenylene oligomers were subjected to benzannulation through ruthenium(0) catalyzed cycloaddition with butadiene followed by acid-catalyzed double dehydration. Further dehydrogenation under Scholl oxidation conditions furnished nanographene materials. This approach employs relatively inexpensive ruthenium catalysts, and stoichiometric organometallic reagents are not required. This benzannulation of tris-thiophene containing 1,2-diols were also subject to benzannulation to prepare triopodal oligophenylenes terminated with thiophenes. Dimerizaiton of these united via lithiation and cuprate formation provided helical dimerized product.