The efficiency of 2 as precursor of benzo [b]biphenylyne 1 was evaluated by means of trapping experiments with typical dienes, such as furans and cyclopentadienones (Scheme 3). In particular, treatment of 2 with CsF in the presence of excess furan (or 2,5-dimethylfuran) successfully afforded the corresponding [4+2] adducts 8a and 8b in 90% and 89% isolated yields, respectively. On the other hand, the reaction of 2 with the polycyclic cyclopentadienone 9 under aryne-forming conditions followed by heating of the resulting adduct 10 in refluxing 1,1,2,2-tetrachloroethane allowed the isolation of 11 in an excellent 94% yield, as the result of a Diels-Alder reaction between aryne 1 and diene 9, and subsequent cheletropic extrusion of CO. Next, we tested the performance of 1 under the conditions developed by our group for palladiumcatalyzed [2+2+2] cycloaddition reactions of arynes. 4b,17 Thus, treatment of 2 with CsF in the presence of catalytic amounts of Pd(PPh3)4 resulted in the formation of a yellow solid, scarcely soluble in common organic solvents, which was identified as the cyclobutadiene-containing starphene 12 on the basis of its high resolution mass spectrum (Scheme 4). When the reaction was performed in the presence of dimethyl acetylene dicarboxylate (DMAD), compound 13 was isolated in a 79% yield, as the result of a [2+2+2] cycloaddition between two molecules of aryne 1 and one of the electron-deficient alkyne. In accordance to previous results with other arynes, 17b,26 the use of Pd2(dba)3 as the catalyst resulted in the selective formation of dibenzobiphenylene 14 by means of the reaction of one molecule of the aryne and two of the alkyne (Scheme 4). Once proved the efficiency of triflate 2 as precursor of 2,3-didehydrobenzo [b]biphenylene (1), and the utility of this novel aryne for the easy access to π-extended cyclobutadiene-containing polycyclic conjugated systems, we decided to explore the use of this building block for the synthesis of oligoacene derivatives incorporating cyclobutadiene rings (CBDoligoacenes). Elegant synthetic strategies recently developed by Swager, Xia, 8c,d,e Miao 8f or Gribble have allowed the access to CBD-oligoacenes functionalized with large phenyl, alkyl and/or (trialkylsilyl)ethynyl substituents, as analogues of acenes in which the presence of four-membered rings into the linear π-backbone increases the number of Clar sextets, resulting in higher stability. The influence of the substituents in the molecular packing and electronic properties has been illustrated by some high-mobility derivatives, 8d,e while the effect of the extension and (anti)aromaticity of the polycyclic conjugated core in charge transport has also been theoretically studied. With those precedents in mind, and on the basis of our own work in the synthesis of long acenes, 28 we decided to approach the construction of unsubstituted (or barely substituted) CBDoligoacenes from adequate endoxide-precursors, which would be accessed by iterative Diels-Alder reactions between biphenylene-based arynes and furans (or isobenzofurans). The highly reactive isobenzofurans I could be easily generated by gentle warming of epoxyacenes II, obtained by reaction of arynes III with furans, in the presence of 3,6-bis(pyridyl)-1,2,4,5-tetrazine (BPTZ) (Figure ). This approach was used in this work for accessing isobenzofuran (15a) and derivatives 15b, 15c, 16, 17a and 17b. As a proof of concept of our approach we first studied the reaction of biphenylyne 18, whose generation from triflate 19 had been previously reported by our group, with isobenzofuran 16 obtained from endoxyde 20. The reaction afforded the epoxy-derivative 21 in a satisfactory 74% yield. Deoxygenative aromatization of 21 was successfully achieved by treatment with catalytic amounts of ammonium perrhenate in the presence of triphenylphosphite as oxygen scavenger, affording 22 as a white, highly insoluble solid in 70% yield (Scheme 5). The identity of 22 was deduced on the basis of its HRMS and UV-vis spectra (see SI), being diagnostic the red shift of the lowest energy absorption band of 22 (lmax = 451 nm) with respect to that of 21 (lmax = 388 nm). The low solubility of 22 precluded the analysis by 1 H NMR. Scheme 5. Synthesis of bis(benzocyclobuta)anthracene 22 by iterative Diels-Alder reactions of biphenylyne (18). Next, we studied the cycloaddition of benzo [b]biphenylyne ( ) generated by fluoride-induced decomposition of triflate 2, with in situ generated isobenzofurans 15, 16 and 17, obtaining the expected cycloadducts 23-25 in satisfactory yields, ranging from 42% for 23b to 73% for 23a (Scheme 6), as perfectly stable and soluble products which could be fully characterized. The deoxygenative aromatization of 23-25 was successfully performed by rheniumcatalyzed procedure mentioned above or by treatment with HCl and iPrOH (effective for the dimethylsubstituted 25b), to afford the expected CBDoligoacenes 26-28 in good yields (Scheme 6).