Nickel‐Catalyzed Coupling of Aryl O‐Carbamates With G rignard Reagents: 2,7‐Dimethylnaphthalene

Abstract

2, 7‐Dimethylnaphthalene R 2, 7‐Dihydroxynaphthalene I 2, 7‐Bis (diethylcarbamoyloxy) maphthalene P 2, 7‐Dimethylnaphthalene

Synthesis and Chiroptical Properties of Hexa‐, Octa‐, and Deca‐azaborahelicenes: Influence of Helicene Size and of the Number of Boron Atoms

“…Following a similar synthetic route, we obtained a series of azaborahelicenes containing different numbers of fused cycles in a helicene backbone and different numbers of boron atoms, namely azabora[6]helicene 1a , azabora[8]helicene 1b , bis-azabora[6]helicene 1c , and bis-azabora[10]helicene 1d (Figure 1 and Scheme 2). …”

“…2b was prepared as described in Scheme 3. A Wittig reaction starting from the benzo[c]phenanthrylmethyl-phosphonium bromide 3b [10] and 2-fluoro-5-(pyridine-2-yl)benzaldehyde 4b [8a] yielded stilbene derivative 5b in 92% yield. Then a photocyclization reaction in a highly diluted toluene solution under irradiation for 16 hours using a mercury lamp with in situ oxidation (using catalytic amounts of iodine under air) generated the target racemic ligand 2b in 56% yield.…”

“…[11] Taking advantage of the 4-cycles increase upon the double cycloborylation, we examined the preparation of bis-azabora[10]helicene 1d from the [6]helicene ligand 2d substituted with two 2-pyridyl groups in the inner 1,16 positions. 2d was prepared as demonstrated in Scheme 3.…”

“…Strong chiroptical properties, blue fluorescence and circularly polarized luminescence (CPL) of these readily prepared novel heterohelicenes are examined and analyzed with the help of quantum-chemical calculations in terms of the size of the helicene and number of heteroatoms, and compared with previously described platina[ n ]helicenes ( 1a 1 – c 1 , Figure 1), [8a,b,e,f] as well as the novel bis-platina[10]helicene 1d 1 .…”

Regioselectivity of Diels–Alder reactions between 6,7-dehydrobenzofuran and 2-substituted furans

“…Thus, commercially available 3- bromophenol was first protected as its carbamate 11 with N , N -diethylcarbamoyl chloride in pyridine in quantitative yield. 10 The ortho bromine was then introduced with 1,2-dibromoethane via directed ortho metallation (DoM) 11 using LiTMP to afford the desired o -dibromobenzene 12 in 75% yield.…”