The synthesis of some benzo[4,5]cyclohept[1,2,3-ij]isoquinolines

A facile synthesis and spectroscopic properties of various oxidation states of the novel benzo[4,5]cyclohept[1,2,3-ij]isoquinoline system are described. The synthesis involves the condensation of 5H-dibenzo[a,d]cyclohepten-5-one, or of its 10,11-dihydro derivative, with amino-acetaldehyde diethylacetal, followed by treatment of the resultant imines with polyphosphoric acid to afford the novel tetracyclic system in high yields.     

Facile synthesis of benzo[4,5]furo[3,2-c]pyridines via palladium-catalyzed intramolecular Heck reaction

The heating of 4-chloropyridine with 2-bromophenol in either neat or DME as solvent gives rise to 2-bromophenoxy pyridines, which were treated with Pd(OAc)₂ and various ligands to afford functionalized benzo[4,5]furo[3,2-c]pyridines.     

A new route to benzo[4,5]cyclohepta[1,2-b]naphthalenes: synthesis of radermachol

[formula: see text] Condensation of 3-phenylsulfonyl-1,3-isobenzofuranone (3) with benzocyclohept-6,7-en-5-ones such as 4 and 15 provides a straightforward, general method for synthesis of functionalized benzo[4,5]cyclohepta[1,2-b]naphthalenes (e.g., 5 and 16). This finding was used to achieve a brief and efficient preparation of 6,7-benzo-3,4-(1,4-dimethoxy-2,3-naphtho)-1,5-dioxosuberane (2), an established intermediate to the naturally occurring red pigment radermachol (1).     

A concise synthesis of novel naphtho[a]carbazoles and benzo[c]carbazoles

Starting from simple indole precursors the synthesis of naphtho[a]carbazoles and benzo[c]carbazoles is described. Key steps include the use of the Suzuki-Miyaura reaction to afford 2- or 3-aryl substituted indoles, as well as a potassium t-butoxide and light assisted aromatic ring-forming reaction.     

The synthesis of phenanthro[4,5-bcd]thiophene and the four monomethylphenanthro[4,5-bcd]thiophenes

The synthesis of phenanthro[4,5-bcd]thiophene and the four monomethylphenanthro[4,5-bcd]thiophenes is described.     

Catalyst-free rapid synthesis of benzo[4,5]imidazo[1,2-a]-pyrimidine-3-carboxamides via four-component coupling in one pot

A new class of fused tricyclic benzo[4,5]imidazo[1,2-a]-pyrimidine-3-carboxamide derivatives was synthesized via an environmentally benign one pot sequential four-component condensation reaction of an amine, 2,2,6-trimethyl-4H-1,3-dioxin-4-one, an aldehyde and 1H-benzo[d]imidazol-2-amine without using catalyst in good yields.     

The preparation of the benzo[4,5]cyclohepta[1,2-b]pyrazine and benzo[4,5]cyclohepta[1,2-b]quinoxaline systems

Benzo[4,5]cyclohepta[1,2-b]quinoxaIine 2 , benzo[4,5]cyclohepta[1,2-b]pyrazine 3a and benzo[4,5]cyclohepta[1,2-b]quinoxaline 4 were prepared from 4,5-benzotropolone and 1,2-phenylenediamine, ethylenediamine and 1,2-diaminocyclohexane, respectively. Compound 3a was methylated to 3b .     

Synthesis of benzo[4,5]phenaleno[1,9-bc]thiophene and benzo[4,5]phenaleno[9,1–6c]thiophene

Two pentacyclic thiophenes, benzo[4,5]phenaleno[1,9–6c]thiophene ( 1 ) and benzo[4,5]phenaleno[9,1-bc]-thiophene (2) were synthesized via the corresponding 3-methylphenanthro[2,1-b]thiophene (7) and 1-methylanthra[2,1–6]thiphene ( 19 ).     

Selective synthesis of benzo[4,5]imidazo[2,1-a]isoquinolines via copper-catalyzed tandem annulation of alkynylbenzonitriles with 2-Iodoanilines

An efficient copper-catalyzed cascade cyclization reaction for selectively synthesizing a variety of benzo[4,5]imidazo[2,1-a]isoquinoline derivatives has been developed. The reaction features the formation of three different CN bonds in sequence. In the presence of Cu(OAc)₂ and KO^tBu, o-alkynylbenzonitriles and 2-iodoanilines proceeded smoothly to obtain the corresponding benzo[4,5]imidazo[2,1-a]isoquinolines in moderate to good yields.     

Synthesis of benzo[3,2]phenanthro[4,5-bcd]thiophene and chryseno[4,5-bcd]thiophene

Benzo[2,3]phenanthro[4,5-bcd]thiophene and chryseno[4,5-bcd]thiophene were synthesized, so that their mutagenic and carcinogenic activity can be determined.     

Synthesis and Diels-Alder reactions of the benzo[4,5]thieno [2,3-c]pyrrole ring system

The first synthesis of the parent compound of the benzo[4,5]thieno[2,3-c]pyrrole ring system and its derivatives, as well as their Diels-Alder reactions with DMAD and N-phenylmaleimide are reported. A new synthesis of the benzo[4,5]thieno[2,3-d]pyridazine ring system is also described.     

A new synthesis of benzo[f]ninhydrin

A new four step synthesis of benzo[f]ninhydrin is described. This method utilizes affordable, readily available materials and reagents and is amenable to large scale production.     

The synthesis of all of the monomethyl isomers of benzo[b]naphtho[1,2-d]thiophene

All isomers of the monomethylbenzo[bnaphtho[1,2-d]thiophenes were synthesized by photocyclization of 2-styrylbenzo[b]thiophenes which were prepared by the Wadsworth-Emmons reaction or the Wittig reaction.     

Facile preparation of benzo[4,5]thieno[2,3-b]pyridines and naphtho[b-4,5]thieno[2,3-b]pyridines via the reaction of Barton esters and benzynes

Titled compounds were prepared in a one-pot synthesis by generating symmetrically substituted benzyne intermediates by the diazotization of anthranilic acids in the presence of Barton esters. Unsymmetrically substituted aryne either gave mixtures of regioisomers or failed. However, nitro and methyl derivatives of titled compounds could be obtained as single products using appropriately substituted Barton esters.     

Facile assembly of fused benzo[4,5]furo heterocycles

A concise synthesis of fused benzo[4,5]furo heterocycles 18 has been developed. Chemo/regioselective Suzuki coupling between 1,2-dihaloarene 17 and alpha-hydroxyphenylboronic acid or ester 20 gives biaryl phenol 19, which then undergoes copper(I) thiophene-2-carboxylate (CuTC)-mediated intramolecular cyclization to afford 18 in good overall yield. This method has broad substrate scope and allows facile assembly of a wide variety of benzo[4,5]furo heterocycles.     

Synthesis of benzo[4,5]imidazo[2,1-a]phthalazines

5,9-Disubstituted benzo[4,5]imidazo[2,1-a]phthalazines are synthesized efficiently from acylbenzoic acids and 2-nitro-5-chlorophenylhydrazine. Nucleophilic substitution in phthalazinones gave a variety of the title compounds after reduction and cyclization.     

A concise synthesis of functionalized 7-oxa-[5]-helicenes

A practical procedure for the preparation of functionalized 7-oxa-[5]-helicenes from 2,7-dihydroxynaphthalene is described.     

A convenient new synthesis of benzo[a]pyrene

A convenient new synthesis of the ubiquitous environmental carcinogen benzo[a]pyrene (BaP) is described. In the key step, the method entails Suzuki coupling of naphthalene 2-boronic acid with 2-bromobenzene-1,3-dialdehyde and requires only three steps. It is considerably shorter and simpler than the older methods and provides BaP in higher overall yield.