Naphtho cyclobutene

An example is the preparation of naphtho(/ )cyclobutene shown above.In a different kind of reaction, five-membered cyclic sulfones can be converted to cyclobutenes by treatment with butyllithium followed by LiAlH4 example. 

Cava has noted that pyrolysis of the sulphones (187) gives the benzocyclobutenes (188). The reaction presumably proceeds by extrusion of sulphur dioxide and recyclization of the intermediate o-quinonemethides. Extrusion of tellurium from the readily available heterocycles (189) and (190) at 500 C gives the benzo- and naphtho-cyclobutenes (191) and (192). The monoazabiphenylenes (193) and (194) have been prepared by pyrolysis of the triazaphenanthrenes (195) and (196). ... 

Gold-catalysed cycloisomerization of l,7-diyn-3,6-bis(propargyl carbonate)s provide for a diastereoselective synthesis of naphtho[ ]cyclobutenes by a cascade sequence involving gold-catalysed double [3,3]-rearrangement, 6 r-electrocyclic reaction, and a decarbonylative cyclization (Scheme 15). °... 

The initially generated o-diallenylarene 273 electrocydizes to the annelated o-xyly-lene 274, which can either ring close to a naphtho[fo]cyclobutene or be trapped with a dienophile to yield the Diels-Alder adduct 275. Instead of the terminal hydrogen atom, the ethynyl functions can also carry alkyl and aryl substituents. 

The thermal [2 + 2]-cycloaddition of allenyne 68 was used for the preparation of a naphtho[a]cyclobutene skeleton 69 [66]. 

In the same way that benzocyclobutene (89) may be prepared by desulfonylation of l,3-dihydrobenzo[c]thiophene 2,2-dioxide, the following compounds may also be prepared 3,4,5,6-tetrabromo-benzocyclobutene 95 naphtho[6]cyclobutene (92a) (>60% yield) 96... 

The same procedure was used to prepare naphtho[6] cyclobutene (6) from (4) in unreported yield. 

Naphthalene, 506, 533 Naphthalene-Lithium, 415 Naphthalene 1,2-oxide, 358 Naphthojfc] cyclobutene, 550 Naphthojh] -cyclopropene, 477, 478 Naphthols, 503 Naphtho [ 1,8-Ac] -pyiane, 85 1,4 Naphthoquinones, 187 1,5-Naphthoquinones, 170 N-(1-Naphthyl)acetamides, 3 a-Naphthyldiphenylmethyl chloride, 415 a-Naphthyldiphenylmethyl ethers, 415... 

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