Autocorrelated 13c-13c double quantum coherence two-dimensional nmr spectroscopy: Utilization of a modified version of the technique as an adjunct in the total assignment of the 1h- and 13c-nmr spectra of the mutagen phenanthro[3,4-b]thiophene

Development of successively higher field nmr spectrometers has facilitated the study of increasingly more complex molecules, although smaller molecules such as phenanthro[3,4-b]thiophene still offer very substantial assignment problems because of the highly congested nature of their ¹H- and ¹³C-nmr spectra. Assignments of such spectra, if they are to be unequivocal, frequently require the utilization of two-dimensional nmr spectroscopic techniques. Total assignments of the ¹H- and ¹³C-nmr spectra of phenanthro[3,4-b]thiophene are reported. Assignments were based on a conventional high resolution 500 MHz ¹H-nmr spectrum, autocorrelated two-dimensional ¹H-nmr spectra (COSY), two-dimensional ¹H-¹³C chemical shift correlation spectra and a modified version of autocorrelated ¹³C-¹³C double quantum coherence two-dimensional nmr spectroscopy. From NOE measurements, a separation of 1.99 Å between H1 and H11 was computed, suggesting that phenanthro[3,4-b]thiophene has a pronounced helical conformation in solution.     

Benzannelated analogs of phenanthro[1,2-b]- and [2,1-b]thiophene: Synthesis and structural characterization by two-dimensional NMR and X-ray techniques

Syntheses of benzo[3,4]phenanthro[1,2-b]thiophene, benzo[3,4]phenanthro[2,1-b]thiophene and their 1-methyl analogs are reported as potential constituents of solvent refined coal liquids and for mutagenicity testing. The attempted synthesis of the 13-methyl analogs which gave the 11-methyl isomers is also described. Total assignments of the ¹H- and ¹³C-nmr spectra based on long range optimized heteronuclear protoncarbon two-dimensional chemical shift correlation are reported. Carbon assignments obtained for benzo[3,4]-phenanthro[1,2-b]thiophene using this approach were confirmed with a 125 MHz ¹³C–¹³C INADEQUATE spectrum. X-Ray crystal structures were determined for benzo[3,4]phenanthro[1,2-b]thiophene and 1-methyl-benzo[3,4]phenanthro[2,1-b]thiophene. Both molecules were helically distorted from planarity. Close intramolecular contacts between the bay region H1–H13 and ClMe-H13 of 2.03 and 2.28 Å, respectively, were responsible for the distortions. There were no close intermolecular contacts of <3.5Å. both molecules refined to an R value of <0.05.     

Two-dimensional relayed coherence transfer experiments as a means of subgrouping protonated carbon resonances of complex polynuclear heteroaromatics on the basis of vicinal proton-proton connectivities

Application of autocorrelated homonuclear (COSY) and proton-carbon chemical shift correlation two-dimensional nmr experiments to the problem of assigning the ¹H- and ¹³C-nmr spectra of phenanthro[4,3-a]dibenzothiophene fails despite their considerable utility in the assignment of the spectra of the smaller phenanthro[b]thiophenes. The failure of these techniques in the case of phenanthro[4,3-a]dibenzothiophene is predominantly due to the inability of the COSY spectrum to provide the means of subgrouping the proton resonances into their component spin subsystems. Two-dimensional relayed coherence transfer nmr experiments which first established coherence between vicinally coupled protons which is then transferred to the carbon spins which are ultimately observed circumvent these problems. The application of two-dimensional relayed coherence transfer to phenanthro[4,3-a]dibenzothiophene is described, the technique leading to the sub-grouping of all five of the proton spin subsystems and thus providing a means of beginning the total assignment.     

Synthesis of phenanthro[b]thiophenes

All isomers of the parent phenanthro[b]thiophenes, namely, phenanthro[1,2-b]thiophene, phenanthro-[2,1-b]thiophene, phenanthro[2,3-b]thiophene, phenanthro[3,4-b]thiophene, phenanthro[3,4-b]thiophene, phenanthro[4,3-b]thiophene and phenanthro[9,10-b]thiophene have been synthesized.     

Synthesis of benzo[b]phenanthro[d]thiophenes

The synthesis of benzo[b]phenanthro[1,2-d]thiphene ( 1 ), benzo[b]phenanthro[4,3-d]thiophene ( 2 ), benzo-[b]phenanthro[2,1-d]thiophene ( 3 ) and benzo[b]phenanthro[3,4-d]thiophene ( 4 ) from appropriately substituted olefines by photochemical cyclodehydrogenation is described. The photolysis of olefin 9 gave a mixture of 4 and anthra[1,2-b]benzo[d]thiophene ( 5 ).     

The synthesis of novel polycyclic heterocyclic ring systems. 2. Naphmo[2,1-b:4,3-g]bisbenzo[b]thiophene

The novel polycyclic heterocyclic ring system, naphtho[2,1-b:4,3-g]bisbenzo[b]thiophene was synthesized from 5-[2-(2-bromo-3-thienyl)ethenyl]naphtho[2,1-b][1]benzothiophene. The assignment of its ¹H and ¹³C nmr spectra was also accomplished by utilizing two-dimensional nmr methods.     

The synthesis of benzo[b]phenanthro[d]thiophenes and anthra[b]benzo[d]thiophenes

The synthesis of benzo[b]phenanthro[2, 3-d]thiophene ( 5 ), benzo[b]phenanthro[4, 3-d]thiophene ( 6 ), benzo-[b]phenanthro[2, 1-d]thiophene ( 9 ), benzo[b]phenanthro[3, 2-d]thiophene ( 14a ), anthra[1, 2-b]benzo[d]thiophene ( 24 ), anthra[2, 3-b]benzo[d]thiophene ( 29 ) and anthra[2, 1-b]benzo[d]thiophene ( 30 ) is described as well as the preparation of 13-methylbenzo[b]phenanthro[3, 2-d]thiophene ( 14b ).     

K-region oxides and imines of benzo[b]phenanthro[2,3-d]thiophene and benzo[b]phenanthro[3,2-d]thiophene

The syntheses of the K-oxides and K-imine derivatives of benzo[b]phenanthro[2,3-d]thiophene and benzo-[b]phenanthro[3,2-d]thiophene are described. The parent hydrocarbons 1 and 2 were oxidized with osmium tetroxide and sodium metaperiodate, and the dialdehydes 12 and 18 so formed, cyclized to the corresponding epoxides 1a,12b-dihydrobenz[b]oxireno[9,10]phenanthro[2,3-d]thiophene ( 7 ) and 1a,12b-dihydrobenz-[b]oxireno[9,10]phenanthro[3,2-d]thiophene ( 13 ). Reaction of the oxiranes with sodium azide gave mixtures of azido-alcohols that, in turn, were transformed to the thiaarene imines 1a,12b-dihydro-1H-benz[b]azirino-[9,10]phenanthro[2,3-d]thiophene ( 8 ) and 1a,12b-dihydro-1H-benz[b]azirino[9,10]phenanthro[3,2-d]thiophene ( 14 ), respectively, with the aid of tri-n-butylphosphine.     

The synthesis of novel polycyclic heterocyclic ring systems via photocyclization. 19. Thieno[3′,2′:4,5]thieno[2,3-c]-naphtho[1,2-f]quinoline,thieno[3′,2′:4,5]thieno[2,3-c]naphtho-[1,2-f][1,2,4]triazolo[4,3-a]quinoline and thieno[3′,2′:4,5]-thieno[2,3-c]naphtho[1,2-f]tetrazolo[1,5-a]quinoline

Photocyclization of 3-chloro-N-(3-phenanthryl)thieno[2,3-b]thiophene-2-carboxamide ( 5 ) yielded only one of the two possible structural isomers, thieno[3′,2′:4,5]thieno[2,3-c]naphtho[1,2-f]quinolin-6(5H)-one ( 6 ), which was further elaborated to afford the unsubstituted ring system 10 , its triazole 11 and tetrazole 12 . The structural confirmation of 10 was achieved by the total assignment of its ¹H and ¹³C nmr spectra by the concerted utilization of two-dimensional nmr spectroscopic methods.     

Assignments of the 1H and 13C NMR spectra of pseudo-symmetric heterocyles using the HMQC-TOCSY experiment to differentiate overlapping spin systems

The ¹H nmr spectra of phenanthro[9′,10′:4,5]thieno[2,3-c]quinoline, benzo[f]phenanthro-[9′,10′:4,5]thieno[2,3-c]quinoline and benzo[h]phenanthro[9′,10′:4,5]thieno[2,3-c]quinoline are highly congested. For each compound, all protons abide in an aromatic environment complicated by pseudo-symmetric regions which result in multiple overlap of the different spin systems these molecules contain. We illustrate here the utility of the HMQC-TOCSY experiment to identify spin systems when the proton spectrum is highly congested. To complete the assignment of the ¹H and ¹³C nmr spectra of each compound the HMBC experiment is used to assign the quaternary carbons.     

The synthesis of novel polycyclic heterocyclic ring systems via photocyclization. 5. [1]Benzothieno[2,3-c]naphtho[2,1-f]-quinoline and [1]benzothieno[2,3-c]naphtho[1,2-g]quinoline

Two previously unknown heterocyclic ring systems, namely, [1]benzothieno[2,3-c]naphtho[2,1-f]quinoline ( 4 ) and [1]benzothieno[2,3-c]naphtho[1,2-g]quinoline ( 5 ) were synthesized via photocyclization of 3-chloro-N-(2-phenanthryl)benzo[b]thiophene-2-carboxamide ( 8 ) followed by chlorination and dechlorination. The total assignment of their ¹H- and ¹³C-nmr spectra was determined by utilizing inverse-detected HMQC and HMBC two-dimensional nmr spectroscopic methods.     

Assignment of the 1H- and 13C-NMR spectra of congested helicenes using two-dimensional NMR methods: Phenanthro[3′,4′:3,4]phenanthro[2,1-b]thiophene

Phenanthro[3′,4′:3,4]phenanthro[2,1-b]thiophene has been prepared and its highly congested proton and carbon nmr spectra assigned. The nmr assignments required concerted utilization of two-dimensional nmr techniques which included: COSY, direct and long range optimized heteronuclear chemical shift correlation and heteronuclear relayed coherence transfer.     

Nuclear magnetic resonance data of pyrido[2,3-B] pyrazines and their σ-adducts with amide ion and water

¹³C nmr spectral data of the parent substance pyrido[2,3-b]pyrazine and several of its derivatives (containing one or more chloro, amino, oxo, bromo, fluoro, phenyl, methyl, hydrazino or t-butyl substituents) are reported. The ¹³C nmr spectrum of the parent substance has been assigned conclusively by ¹³C-labelling. Additionally we proved, the existence of anionic 1:1 σ-adducls i.e., 3-amino-3,4-dihydropyrido[2,3-b]pyrazine, the formation of 3-amino-2-t-butyl-6-chloro-3,4-dihydropyrido[2,3-b]pyrazinide ion and by ¹H nmr spectroscopy 2-amino-1,2-dihydro-3-phenylpyrido[2,3-b]pyrazinide ion. The ¹³C nmr data of the cation of the dihydrale 2,3-dihydroxy-1,2,3,4-tetrahydropyrido[2,3-b]pyrazine, present in a solution of the parent compound in N hydrochloric acid, are given.     

Total assignment of the 1H and 13C NMR spectra of pyrrolizino-[3,4,5-a,b]isoquinoline,benzo[1,2]pyrrolizino[3,4,5-a,b]isoquinoline and 2-methylthiopyrrolizino[3,4,5-a,b]isoquinoline

The total ¹H and ¹³C nmr spectral assignments of pyrrolizino[3,4,5-a,b]isoquinoline, benzo-[1,2]pyrrolizino[3,4,5-a,b]isoquinoline and 2-methylthiopyrrolizino[3,4,5-a,b]isoquinoline are reported. The concerted use of the COSY, HMQC, HMBC and nOe-difference experiments is used to generate total assignments of the ¹H and ¹³C nmr spectra.     

Nitration of dithieno[3,4-b:3′,2′-d]pyridine and dithieno[2,3-b:3′,2′-d]pyridine

The nitration of dithieno[3,4-b:3′,2′-d]pyridine ( 2 ) and dithieno[2,3-b:3′,2′-d]pyridine ( 3 ) has been studied. Nitration of 2 occurred in both positions of the c-fused thiophene ring, while 3 was predominantly substituted in the 2-position. The structures of the nitro derivatives were proven by extensive use of ¹H and ¹³C nmr spectroscopy.     

Polycondensed nitrogen heterocycles. Part 21. Complete 13C NMR assignment of annelated phenanthridines

Two-dimensional nmr techniques were used for the complete assignment of ¹³C nmr spectra of pyrrolo-[1,2-f]-, pyrazolo[1,5-f]-, and 1,2,4-triazolo[1,5-f]phenanthridines.     

Complete assignment of the 1h- and 13c-nmr spectra of [1]benzothieno[2,3-c]naphtho[1,2-h]quinoline and [1]benzothieno[2,3-c]naphtho[1,2-h][1,2,4]triazolo[4,3-a]quinoline. Concerted use of two-dimensional nmr techniques

The ¹H- and ¹³C-nmr spectra of [1]benzothieno[2,3-c]naphtho[1,2-h]quinoline and [1]benzothieno[2,3-c]-naphtho[1,2-h][1,2,4]triazolo[4,3-a]quinoline were totally assigned using a combination of two-dimensional nmr techniques. After correlation of the proton signals by a COSY spectrum and one-bond heteronuclear correlation, complete assignment of the ¹H- and ¹³C-nmr spectra of the novel heterocyclic compounds required the application of long-range CH coupling information particularly for quarternary resonance assignments and the orientations of individual spin systems relative to one another.     

Etude de la décomposition thermique d'azido dithiényl-1,2 éthènes et éthanes

Thermal decomposition of azido-1,2-dithienylethenes 1 gave thienyl 4H-thieno[3,2-b]pyrroles 3 . For the 3,4-disubstituted thiophene derivatives 2 , the same reaction led to the amino-1,2-dithienylethenes 4 . In contrast, only azido-1,2-dithienylethanes 7 led to thienyl-5,6-dihydro-4H-thieno[3,4-b]pyrroles 8 . The structure of the obtained derivatives was established on the basis of ¹H nmr, ir, and mass spectral data.     

The synthesis of novel polycyclic heterocyclic ring systems via photocyclization. 23 . Naphtho[2′,1′:4,5]thieno‐[2,3‐c]naphtho[2,1‐f]quinoline

A previously unknown heterocyclic ring system, naphtho[2′,1′:4,5]thieno[2,3‐c]naphtho[2,1‐f]quinoline ( 14 ), was synthesized via oxidative photocyclization of 3‐chloro‐N‐(2‐phenanthryl)naphtho[1,2‐b]‐thiophene‐2‐carboxamide ( 9 ). Further elaboration of the lactam 10 yielded the unsubstituted ring system 14 . Structural confirmation of compound 14 was accomplished by a total assignment of its ¹H and ¹³C nmr spectra utilizing the concerted two‐dimensional nmr spectroscopic methods.     

The insertion and extrusion of heterosulfur bridges. XII. Selectivity and side reactions in the bridging process

1-Phenylnaphthalene undergoes sulfur bridging at 500° in the presence of hydrogen sulfide and a heterogeneous catalyst to produce benzo[b]naphtho[1,2-d]thiophene (13%). 3-Methylphenanthrene and 9-formylphenanthrene diethyl acetal ( 7b ) give sulfur bridging to produce phenanthro[4,5-bcd]thiophene, i.e. with loss of the ring substituent. Additionally, 7b hydrogenolyzes to 9-methylphenanthrene. With decadeuteriobiphenyl as a substrate, the dibenzothiophene formed, as well as the biphenyl recovered, is largely devoid of deuterium label. Confirmation that benzene and toluene react under sulfur-bridging conditions is presented.