Naphtho -cyclopropene

Saito reported the extension of Billups tandem silver-catalyzed ring-opening cycloaddition reaction methodology to addition to imines (Scheme 2.45).77 Naphtho- /) cyclopropene 167 added to substituted aryl imines 168 at room temperature in the... 

Treatment of naphtho[. ]cyclopropene 686 with dimethyltrithiocarbonate and with l,3-dithiole-2-thiones affords l,3-dihydrobenzo[2,3-( ]thiophenes 687 and 688, respectively. This reaction involves a [2Jt+2cr]-type cycloaddition process (Scheme 103) <2004H(62)773>. 

Saito also investigated the reaction of naphtho h cyclopropene 167 with troponone-derived imines 170 (Scheme 2.46). Reaction took place to afford tetracyclic dihydroi-soquinolines 171 in modest yields.78 However, the preferred product was the simple addition product 172. The yields of cycloadducts 171 were generally only 8-15%. 

Similar routes have been described to naphtho(b)cyclopropene 15S), and to annelated derivatives 159). 

The first naphtho[a]cyclopropene 68d was also obtained by that route. 3H-indazole was proposed as an intermediate in this reaction 78>. The reaction proceeds equally well from the triplet state of 7. However with acetone light capture from the sensitizer may not have been complete. A trapping of the diradical intermediate 67 to give the known indene 69 by photolysing 7 in dimethyl-acetylene-dicarboxylate (ADC) afforded only a trace of 69. However the yield of 68a was reduced to 40%. Either trapping of 67 was not effective enough or ADC may have acted as quencher. Trapping with furan or cyclopentadiene was also not effective 78a). 

Benzocyclopropene (88) and naphtho[h]cyclopropene react with various alkenic substrates to give cy-cloaddidon piquets in the presence of silver ion. Reaction of (88 equation 39) with butadiene assisted by 1 mol % of AgBp4 in benzene (0 C, 30 min) gives (89) and (90). Dimethylallene (91 equation 40) and oct-4-yne (95 equation 41) also react readily with (88) in the presence of silver ion to give the corresponding cycloaddition products (92), (93) and (96), together with acyclic products (94) and (97). 

The reaction of naphtho[b]cyclopropene (67) with Fc2(CO)9 in chloroform at 25 °C yields a yellow crystalline (Ci2HgO)Fe(CO)4 product (68) in 27 % yield, resulting from the addition of an Fe-C bond of Fe(CO)s across one edge of the three-membered ring (equation 45) 2c... 

Dehydrohalogenation. Billups and Chow have prepared naphtho[h]-cyclopropene (2) by the method used previously to prepare benzocyclopropene (4,402). Other base—solvent systems were less successful. 

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... 

A diradical intermediate has been detected by ESR in the photolysis of naphtho[fc]cyclopropene in hydrocarbon solvents. ... 

H12O2 f Tricyclo[5.3.0.02- ]decan-3,8-dione, 3OB, 108 oHi2O2 f Tricycloi 5.3.0.02- ]decane-4,9-dione, 40B, 164, H7Br, 1-Bromo-iH-cyclobutaide]naphthalene, 43B, 183 iHfl, Naphtho[b]cyclopropene, 39B, 118... 

Imine 145 also underwent the [3+2] annulation reaction with naph-tho[f ]cyclopropene to give product 146 in the presence of both Ag and Yb salts (Scheme 2.106) [161]. Reaction of naphtho[f ]cyclopropene with tropone under similar conditions has also been reported [162]. 

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