HELICAL METALLOCENE OLIGOMERS AND A METHOD FOR THEIR PREPARATION

Abstract: A helicene compound having the structure (I), which contains seven six-membered conjugated aromatic rings capped by two five-membered rings which do not superimpose on each other. The invention also describes a helical metallocene oligomer capped by unsaturated five-membered rings, having the structure (II), wherein M is a transition metal halide and n=1 to 100. Method for the preparation of these compounds are also presented.

Description: HELICAL METALLOCENE OLIGOMERS AND A METHOD FOR THEIR PREPARATION Background of the Invention The invention described herein was made in the course of work under Grant No. DMR-82-13794 from the National Science Foundation. The U.S. Government has certain rights in this invention. Throughout this application various publications are referenced by arabic numerals within parentheses. Full citations for these references may be found at the end of the specification immediately preceding the claims. The disclosures of these publications in their entire¬ ties are hereby incorporated by reference into this application in order to more fully describe the state of the art as known to those skilled therein as of the date of the invention described and claimed herein. Attempts have been made in the past to synthesize poly¬ mers like &, in which conjugated arrays and metal atoms alternate. One such attempt resulted in the formation of compounds in which the bonds created in the polymer¬ ization process were between carbon atoms and when applied to preparations of polyferrocenylenes (struc¬ ture fi) gave small oligomers that were well character- ized (14) and larger polymers that were sometimes im¬ pure (15,16) . In other experiments, the carbon-metal bonds were cre¬ ated in the polymerization process, and when applied to reactions of transition metal salts with dilithium as,- In other experiments, the carbon-metal bonds were cre¬ ated in the polymerization process, and when applied to reactions of transition metal salts with dilithium as- indacenide (£ ) gave (C 12 H 8 M *n' where M is Fe ' Co ' or Ni; with dilithium pentalenide (&) (CgHgM) n (here M = Co or Ni) - and with dilithium fulvenide {£ ) ( ιo H 8 M *n' where M » Fe, Co, Ni or Mo. However, the value of n in each of these experiments was 2, i.e. the products were only di ers. A hypothesis for avoiding dimerization was presented. This idea involved incorporating the hydrocarbon sand¬ wiches of the dimers within helicenes. Conjugated helical hydrocarbon dianions capped by five-membered rings were synthesized for the purpose. It was sug¬ gested that reacting these aromatic anions with transi¬ tion-metal halides would produce metallocene polymers. However, the aromatic dianions produced were too small to give polymers. Dimers can form only when the number of extending ben¬ zene rings is few. Monomeric metallocenes (structure £ where M » Fe, Co PF g ~) are formed when the five- membered rings superimpose. overlapping unsaturated five-membered rings which can yield polymeric metallocenes. Brief Description of the Figures Figure 1 depicts the 75 MHz 13 C NMR spectrum of the oligomer having structure fl in CD 3 COCD 3 . The spectrum, measured using 90° pulses and no relaxation delay, is displayed with 5 Hz line broadening. The chemical shifts were measured assuming that of CD 3 COCD 3 to be 29.8 ppm. Peaks assigned to metallocene carbons are pointed out, and the dotted arrows show where the cor- responding resonances appear for the indene analogue (pictured) . The peak marked C m is attributed to the ethylene carbon (labeled on the diagram) . Figure 2 depicts the 200 MHz ^H NMR spectrum of the helicene having structure £ in CDC1 3 . Figure 3 depicts the C NMR spectrum of the helicene having structure £ in CDC1 3 . The resonances of carbons of the five-membered ring are assigned to peaks at 40.2, 130.5, 132.4, 137.7 and 142.9 ppm (see refer¬ ence) . The seven protonated benzenoid carbons are as¬ signed to peaks at 119.6, 122.9, 126.0, 126.3, 126.4, 126.5, and 128.1 ppm. Five of the six quaternary ben¬ zenoid resonances are visible: 126.2, 128.5, 130.3, 130.9, and 132.3 ppm. Figure 4 depicts the CD (solid line) an UV (broken line) spectra of the helicene having structure £ (6.17 x 10~ 6 M) in CH 3 OH. UV peaks (logε ) are at 354 (4.05), 336 (4.16), 278 (4.73), and 252 nm (4.84). CD peaks ( (IIθθll)) aarree aatt 224433 ((e6.48 x 10 4 ), 285 (1.75 x 10 5 ), and 395 nm (-1.0 x 10 5 ) . Figure 5 depicts the CD (solid line, 5 x 10 "6 M) and UV (broken line, 5 x 10 "6 ) spectra of the oligomer having structure fi (M = Co + PFg " ) in CH 3 CN. UV peaks (loge ) are at 486 (4.41), 340 (4.66), and 258 nm (5.11). CD peaks ([θ]) are at 263 (3.30 x 10 6 ) , 382 (-1.19 x 10 6 ) , and 474 nm (-8.40 x 10°) . Figure 6 depicts the chemical reaction and products of each step described in Examples 1-11. Summary of the Invention . The present invention concerns a helicene compound having the structure: which contains seven six-membered conjugated aromatic rings capped by two five-membered rings which do not superimpose on each other. The present invention also concerns a helical metallo- cene oligomer capped by unsaturated five-membered rings, having the structure: wherein M is a transition metal halide and n=l to 100 A method of preparing the helicene is provided which comprises: a) contacting a compound having the structure: < k *°"- wherein R=(t-Bu)Me 2 Si, with 1,4 -bis- [ (CgH 5 ) 3 P+CH2]-2-Br-CgH 3 , under suitable condi¬ tions to form a compound having the structure: b) then, subjecting the compound formed in step (a) to light energy in the presence of an acid scavenger compound which results in a photocyclization; and c) finally, contacting the cyclized product of step (b) with a suitable reducing agent and an acid to form the helicene. A method of preparing the helical metallocene oligomer is also provided which comprises: a) first, contacting the helicene prepared as described above with a suitable base; b) contacting the product resulting from step (a) with a transition metal halide in a suitable solvent; c) contacting the product of step (b) with a suitable oxidizing agent; and d) contacting the product of step (c) with a hexahalo- phosphate salt to produce the helical metallocene oligomer. Detailed Description of the Invention The present invention is a new composition of matter, a polymer comprised of alternating metal atoms and rings of atoms in which the path of conjugation of so- called n -electrons extending from one metal to the next is unbroken either by atoms that do not have available a single π -electron to continue the path of conjugation or in which the carbon skeleton does not constrain the π-electrons on adjacent atoms to almost parallel orbitals. The ~ r -electrons are those valence shell electrons on the skeletal atoms in excess of the one required to bond to each adjacent atom. The invention includes those examples of materials in which the skeleton is coiled in a helix, and those examples in which one of the two directions predominate in which the helices wind. It includes examples of the materials described in the first sentence above that are optically active. It is contemplated that the metals useful in the present invention are any metals chosen from among the transition elements (i.e. groups 3-10 of the most recent revision of Mendeleev's Table of the Elements), the lanthanides or the actinides. An example of the present invention is the polymeric cobaltocinium hexafluorophosphate shown below. Foreseeable uses of the materials of the present invention include those exploiting the electrical, magnetic, and optical properties of the materials and their derivatives. The metallocenes of the present invention may also be the basis for new catalysts that induce high asymmetry in chemical transformations. Scheme I ■a l,4-bis[(C 6 H 5 ) 3 P + CH 2 ]-2-Br-C 6 H 3 , 2Br " (0.5 equiv wt) , LiOEt (1.1 equiv wt) , EtOH, 25°C, 5-12 h, 95-100% yield). ^h , CgHg, I 2 (2.2 equiv wt) , propylene ox- ide, 4-12 h. £ 1) 1-BuLi, tetrahydrofuran, H^C; 2) H 2 0; 3) £-toluenesulfonic acid, CgHg, 80°C, 10 min (45-65% yield from jl) . The preparation of hydrocarbon £, summarized in Scheme I, is easy to carry out (7). The phosphonium salt of step a was prepared from 2-bromo-g-xylene (2.2 equiv * H-bromosuccinimide, 0.008 equiv. dibenzoylperoxide, CC1 4 , reflux, 3h, 75% yield, then 2 equiv. triphenyl- phosphine in DMF, 91% yield. All new compounds exhib- ited satisfactory NMR, IR, and (except for the salts) , mass spectra (including, for key compounds, high reso¬ lution mass spectra) . In the H NMR spectrum of £, as in other helicenes, the olefinic and allylic proton resonances are shifted to higher field than in simpler indenes (1, 3b, 7). The isomers of H in which both ether functions are in the other benzylic position do not give appreciable amounts of helical product, and the one in which the ethers are in the non-benzylic position gives a helical product from which the ethers cannot be eliminated (7) . The method of preparation has three main features. (1) A bromine directs the photocyclization to give the helix by blocking both the position it occupies (C-l) and the position adjacent (C-2) (5) . This atom is then easy to remove. In its absence, the cyclization gives only the planar isomer . and none of the helicene £. Resonances characteristic of £ are absent in the H NMR spectrum of the crude product (7). Propylene oxide is required during the photocyclization to consume the HI generated, thereby preventing the ROH functions from being eliminated prior to cyclization (7) . in the absence of propylene oxide, photo-cyclization of (fi, _&)-& gives helical product, but in a racemic form (7). The direction in which the helix winds is that expected if silyloxyls outside the helix are favored. The heli- city is thus controlled by the stereochemistry of (7). i is prepared from (B)-X [46-52% enantiomeric excess (ee) ] and irradiated in the presence of traces of io¬ dine, it gives helical feia-indene (containing the bro¬ mine) whose [α] D (+ 82°) corresponds to ca. 1% ee. The double bonds in this material are shifted from their position in £ (7) . For the absolute configuration of (fi)-(-)-X see ref. 7. The absolute configuration of £ was assigned on the assumption that, like all helicenes, the (H.)-enantiom- er is levorotatory at 578 nm and exhibits a negative Cotton effect in its CD spectrum in methanol for the band at 395 nm ([ot] = -lxlO 5 deg cm 2 mol "1 ) (7). Its ee was measured by analyzing the H NMR resonances of one of its . CH 2 's when a solution (2.5 mg) in fc) 3 (12mg) measured to have an ee of 60% implies that [a] D max =7000°. Structure (S,S)-i is contacted, e.g. mixed in a suit¬ able solvent, contacted with a suitable reducing agent (e.g. i-Bu i) which eliminates the bromine group and then contacted with an acid (e.g. p.-toluene sulfonic acid) which eliminates the RO-groups and introduces two double bonds. (£, S.) ~~ l of Scheme I gives 27% structure jKa. (recognized by the symmetry of the H NMR after debromination) , 12% ££., and no detectable ( 1 H NMR) endo. endo isomer. The latter could not have been misassigned the exo. ≤xa-structure since the (M)-con¬ figuration requires more asymmetric carbons to have the (E)-stereochemistry than are present in 1 (7). When the helicene £ is combined first with i-butylli- thium and then with CoBr 2 .DME (DME * 1,2-dimethoxyetha- ne) and the product is oxidized in aqueous HC1 with FeCl 3 , added NH^PFg precipitates a red cobaltocinium salt (69% yield after washing with water and ether, and drying) that elemental and spectroscopic analyses indi¬ cate to be an oligomer of structure £ (M - Co + PF g ) (7, 8) . The anion of the salt of the hexaflurophosphate (PF " g) substitutes for the bromines of CoBr 2 . This material is soluble in acetone and acetonitrile, and was purified by adding its solutions in acetone to vigorously stirred ether, then filtering and drying the resulting precipitate. It is unaffected by heating in air at 260°C. Evidence that the cobaltocinium salt is a short polymer of structure fl is the following. The 13C NMR spectrum (Fig. 1) consists of resonances at positions character¬ istic only of benzenoid helicenes (including £) (135- lie ppm), (10) of bis(indenyl)cobalt(III) salts (80-74 ppm) , (11) and of the methylene group of £ (40 ppm, this last peak very small, corresponding to approxi¬ mately two end groups for every 3-4 cobalts) (11) . Figure 1 marks (with dotted arrows) the positions at which the carbon atoms of the five-membered rings of bis(indenyl)cobalt(III) hexafluorophosphate exhibit their resonances, and it shows that the corresponding peaks attributed to structure fl are all 2 ppm to their right. This shift is expected, for when comparing the resonances of carbon-2 ' in [4]-and [7]-helicenes, (the second protonated carbon on the first ring counting from the inside of the helix) the latter (in which this carbon is above another ring) is shifted to higher field by 2 ppm (10) . Another significant feature of the spectra is the absence of resonances around 51.3 ppm, characteristic of l,l'-bi-lfl-indene ["bi(3-inde- nyl)"J, showing that the transition metal ions do not couple the carbanions by oxidation. The elemental analysis corresponds to a composition of 3.13 hydrocarbons, 2.13 CoPFg's, and 3.45 + 1.4 H 2 0*s. The molecular weight is thus £&. 1.9 x 10 . Three independently prepared samples were analyzed. Anal, calcd. for 2.0 H 2 0's: C, 71.65; H, 3.66; Co, 6.65. Found: C, 71.24; H, 3.90; Co, 6.71. Anal calcd. for 4.9 H 2 0's: C, 69.93; H, 3.88; Co, 6.49. Found: C, 69.82; H, 3.73; Co, 6.48. The third sample's analysis corresponded to that of a slightly larger molecule. Anal, calcd. for 3.49 rings, 2.49 CoPFg's, 7.3 H 2 0's: C, 67.96; H, 3.92; Co, 6.61, » F, 12.78. Found: C, 68.18; H, 3.61; Co, 6.63; F, 12.45. For a simple com¬ plex of 2 rings and 1 Co, calcd. is C, 77.84; H, 3.81; Co, 5.30; and for an infinite polymer, C, 65.89; H, 3.07; Co, 8.97. The optical activity is very high, 4.1 (+ 0.6) times as great as that of £. When measured using a sample pre¬ pared from £ whose enantio eric excess (ee) was 60%, [ ] D for cobaltocinium salt of 100% ee is 26,000. The molar ellipticities of the CD peaks at 474 and 263 nm (-8.4 x 10 and - 3.3 x 10 , assuming the molecular weight to be 1.9 x 10 3 ) are 7.2 and 6.0 times as large as for the corresponding peaks in £ (M=Co + pF g ~) (7) . The present invention is further illustrated by refer¬ ence to the examples which follow. These examples are keyed to the reactions and structures depicted in Fig. 6. Example 1 In an oven-dried 2 3-necked round-bottomed flask, fitted with a mechanical stirrer, an argon inlet and a 250mL dropping funnel, was placed 114.4g (0.4mol) 2,7- dibromonaphthalene (Fig. 6, Structure fi) and IL freshly distilled THF. The solution was stirred and cooled to -78° under argon. A solution of n-butyllithium (175mL 2.4M, 0.42mol) in hexanes was injected into the addition funnel and added in drops in 30 min. The greenish-yellow mixture was stirred at -78°C for anoth¬ er 20 min. Dry chlorotrimethylsilane (81m , 69.5g, 0.64mol, distilled from CaH 2 ) was then added in 10 min from the dropping funnel, resulting in an exothermic reaction and a color change to orange. After the exo- therm subsided (£a. 15 min) , the cooling bath was re¬ moved and the mixture was allowed to warm to room tem¬ perature and stirred for 2h. Solvent was evaporated to about 250mL and the mixture was diluted with IL of water. It was then extracted with ether (1 x 600mL, 3 x lOOmL ether) . The combined ether extracts were washed with 200mL brine, dried over anhydrous magnesium sulfate, and filtered. Evaporating the solvent gave 126g (112%) yellow-orange liquid, which when kept at 15°C overnight solidified to a pale yellow mass. This crude product is pure enough for the next step, al¬ though the results of that step imply that 2-bromonaph- thalene is present as an impurity. 1 H NMR (200MHz, CDC1 3 ) : δ 7.99 (dd, J » 1.5, 0.8Hz, 1.01H), 7.88 (d, J=0.8Hz, 0.96H), 7.77 (d, J=8.1, 1.2Hz), 7.67 (d, J=8.7Hz), 7.58 (dd, J=8.1, 1.2Hz) , 7.52 (dd, J=8.7, 2.0Hz) the integral of 7.77-7.52 corresponds to 4.4H 0.32 (s, 8.6H) . EXAMPLE 2 Anhydrous aluminum chloride (70g, 0.526mol, Fisher) was placed in a IL 3-necked flask fitted with a mechanical stirrer, nitrogen inlet, and 250mL addition funnel. Dichloro ethane (lOOmL) and a solution of 61g (0.48mol) 3-chloropropionyl chloride in 50mL dichloromethane were added to the flask while its contents were stirred. The flask was cooled in dry-ice acetone, and a solution of 126g bromosilane (Fig. 6 structure £) in 200mL dich¬ loromethane was added in 35min. The mixture was stirred for lOmin at -78°C and allowed to warm to room temperature during 45min. The reaction mixture was poured into ££. lOOOmL ice containing lOOmL cone, hydrochloric acid. The mixture was extracted with 1.5L dichloromethane, and the aqueous layer was extracted with additional dichloromethane (3x200mL) . The com¬ bined-organic layers were washed once with 1.5L water, dried (MgSO.) , filtered, and evaporated to give 135g crude structure £ as an off-white solid. This was cyclized without further purfication. However, it could be purified by shaking with 500mL petroleum ether and filtering. The pricipitate was then pure structure £ (90g, 76%) , and the filtrate on evaporation gave 44g of dark liquid containing some structure £. For the pure material the m.p. is 120°C and the 1 H NMR (200 MHz, CDC1 3 ): δ : 8.35 (br s, 0.79H), 8.12 (d, J»0.95Hz, 0.79H), 8.02 (dd, J»8.6, 1.7Hz, 1.11H) , 7.87 (d, J=8.6Hz, 1.05H) , 7.75 (d, J»8.9 , 1.05H) , 7 .66 (dd , J=8.8 , 1.8z , 1.05H) , 3 .96 (t, J*6.9Hz , 2.10 H) , 3 .56 ( t , 6 .9Hz, 2.10H) . EXAMPLE 3 Method A: Anhydrous A1C1 3 (35g, Fisher) was weighed into an oven-dried 2L 3-necked flask fitted with a mechanical stirrer, a drying tube the outlet of which is vented to the hood, and a stopper. Concentrated sulfuric acid (325 mL, Mallinckrodt, Electronic grade) was added, and the mixture was stirred in an ice-water bath. Crude structure £ (65g) was added to the suspen¬ sion in small portions in 20min while stirring vigor- ously. The reaction mixture became yellow and then orange. The stopper was replaced with a thermometer and the flask was heated by means of a mantle. When the internal temperature was 65°C, the stirring rate was increased, and rate of heating decreased to control the foaming. After the foaming had subsided, the mix¬ ture was held at 98°C for lh. It was then cooled to c_a. 70°C and cautiously poured into 4L of ice-water containing ice. The mixture was stirred for 2h and extracted with CH 2 C1 2 and filtered through a 6"x5cm column of neutral alumina, eluting with CH 2 C1 2 . The filtrate was evaporated, giving 38.7g (68% from £, 76% from JJ) £ as a pale yellow solid, m.p. 131-132° (lit. 132-134°C) (3b). The 200MHz l E NMR is identical with that of a sample prepared according to the previously published procedure (3b). The IR spectrum also was identical to that reported for structure £ (3b) . Puri¬ fication of crude £ may also be achieved by crystalli¬ zation as shown below. Method B: 89.5g of purified £ was added over 40 min to 300mL concentrated sulfuric acid in a 2L 3-necked flask (the apparatus was the same as in method A above). The reaction mixture was heated to 90°C (internal tempera- ture) and maintained at this temperature for 80min. After cooling, the reaction mixture was poured into ice-water, extracted with CH 2 C1 2 (15x200mL) , the organ¬ ic layer washed with 2L water, dried (MgSO.) , filtered and evaporated. The residue was crystallized from CH 2 Cl 2 -ether, giving 6Ig off-white solid. A second crop of £, 15g was obtained after chromatography of the mother liquor. The total yield of £, 76g, represents a 73% yield from 2,7-dibromonaphthalene. EXAMPLE 4 Lithium aluminum hydride (8.05g, 0.2mol, Aldrich) and dry ether (lOOmL) were placed in a 2L 3-necked flask fitted with mechanical stirrer, 250mL Kontes addition funnel and a dry condenser carrying a N 2 inlet. To the stirred suspension was added during 20min a solution of 35.8g (0.2mol) (+)-N-methyleρhedrine in 350mL dry ether. The reaction mixture was refluxed for lh, cooled, and a solution of 48.9g (0.4mol) 3,5-dimethyl- phenol (Aldrich) in 220mL dry ether was added over a period of 225min. The mixture was again refluxed for lh, cooled in ice-salt-water mixture (internal temp. 0°C) , and 20g £ was added in one portion. The mixture was stirred overnight. Water (lOmL) was added in drops to the reaction mix¬ ture, followed by 400mL 1M hydrochloric acid. After 5 min, the ether layer was separated and the aqueous layer extracted with 200roL ether. The combined ether layer was washed with 1M HC1 (lx300mL), water (lx300mL), 10% NaOH solution (3x200mL), brine (lx500mL), and dried over MgSO^. The solvent was then evaporated to a small volume, and the solid was fil¬ tered giving 11.5g £, [ ct ] 578 20 »-43° (c=0.40, CH 2 C1 2 ) . A second crop (4.1g, [ ct] 578 20 ■ -0.56° (c=0.36, CH 2 C1 2 ) was obtained from the filtrate when pentane was added. Evaporation gave a third portion, 4.3g [α] 576 20 »-9.2°. The NMR spectrum of £ was identical to that of its racemate (3b) . The results of two related experiments are these: (1) from 32.6g ketone there were obtained 23.4g £ with [ g £ with [ £ with [ u ct. j ] 5 0 " 6 The NMR spectra of the O-methylmandelate ester ( 12) and the CD spectrum of the p.-bromobenzoate ester ( 13) show that the (-) -enantiomer has the (£) -conf iguration. EXAMPLE 5 S-(-)-£ (34.9g, 0.133mol), [ ] 578 20» -41° (c=0.4, CH 2 C1 2 ) , was mixed with 30g (0.199mol) t-butyldimethyl- silylchloride (Petrarch Systems) and 28g (0.412 mol) imidazole (Aldrich) in 400mL DMF (Fisher, spectroscopic grade) . The solution was stirred at room temperature under N 2 for 200min, diluted with 800mL ether, and shaken with 2L cold water. The ether layer was washed with brine (2x500mL), dried (MgS0 4 ) , filtered and evap¬ orated, giving an orange oil that eventually solidi¬ fied. This was chromatographed on a silica (6"xl0cm dia.) column, eluting with CH 2 Cl 2 -petroleum ether (1:7). The product eluted quickly, and evaporation gave 51g (102%) white solid, [ ] 578 20 =-50° (c=0.2, CH 2 C1 2 ) . The NMR spectrum of this material was iden¬ tical to that reported for racemic S. (3b) . EXAMPLE 6 S-(-)-S (34.2g, 0.091mol, [ α ] 578 =-50°) was dissolved in IL dry THF and 0.5L dry ether in a 2L 3-necked flask fitted with an Ar inlet, low-temperature thermometer and a septum. The solution was cooled to -78°C under argon and 80mL (0.208mol) of 2.6M n-butyllithium in hexanes was injected through the septum during 5min. The slightly greenish solution was stirred at -78°C for 20min, and then lOOmL dry DMF (distilled from BaO under reduced pressure) was injected. The cooling bath was removed and the solution stirred for 70min. Quenching with 200mL water, extraction with 700mL ether, washing with brine (IL, 2x0.5L, re-extracting with 2x400mL ether) and again with brine (400mL) , drying (MgSO.) , and evaporation gave an oil, which was chromatographed on silica. CH 2 Cl 2 -petroleum ether (1:2) eluted an impurity, and CH 2 Cl 2 -petroleum ether (1:1 to 2:1) eluted the aldehyde X, 25.2g (85%) as a pale yelow solid, [α ] 578 20 »-42.7° (c»0.3, CH 2 C1 2 ) . The NMR spec¬ trum of this material was identical to that of racemic X (3b). EXAMPLE 7 2-Bromo-p-xylene X (46.25g, 0.25mol, Aldrich) was mixed with 98g (0.55mol) N-bromosuccinimide (Fisher) and 500mL carbon tetrachloride in a IL round-bottomed flask. Dibenzoyl peroxide (500mg) was added, and the mixture was refluxed for lOOmin, cooled, filtered, and the filtrate was evaporated to a small volume. Tri- turation with pentane gave a precipitate, which was filtered giving 18.5g white solid, m.p.86°C. A second crop (20.5g) was obtained from the mother liquor. The total yield of £ was 39.Og (45.5%). H NMR (270MHz, CDC1 3 ) δ 7.60 (d, J=2Hz, IH) , 7.42 ( (dd,, J J==77..99HHzz,, 11 HH)) ,, 7.31 (dd, J=7.9Hz, 2Hz, IH, 4.57 (s ( 2H) , 4.40 (s, 2H) . EXAMPLE 8 The tribromide £ (39g) and 63g triphenylphosphine were dissolved in 300mL dry DMF, and the solution was reflu¬ xed for 3h. After cooling, 200mL ether was added, and the precipitate was filtered. The solid was washed with ether to give ~ l as a white fluffy solid, m.p. 260°C. Yield 89.2g (91%). H NMR (300MHz, CD 3 CN) <S : 7.9-7.8 (m, 6H, 7.7-7.45 (m, 24H) , 7.09 (br s, IH) , 7.0-6.95 (dd, J=8.0, 2.4, IH) , 6.9-6.85 (br d, J=8.08) , 4.85 (dd, 4H) . EXAMPLE 9 n-Butyllithium (37mL, 2.4M, 88.8mmol) was injected into a 2L 3-necked flask fitted with argon inlet, mechanical stirrer, and an addition funnel. The flask was cooled to -78°C, and 400mL 200-proof ethanol was added in drops from the funnel during 20min. The solution was then allowed to warm to room temperature. The bis(phosphonium) bromide ¥ (35, 0.040mol) and S- (-)-aldehyde X-(25.2g, 0.077mol) were suspended in 500mL 200-proof ethanol in a 2L 3-necked flask fitted with an Ar inlet, mechanical stirrer, and a septum. During 30min the lithium ethoxide solution prepared above was transferred to the solution via a cannula. The resulting yellow solution was stirred overnight, during which a fine yellow precipitate appeared. The suspension was poured into 2L water, and the mixture was extracted with CH 2 C1 2 (lx600mL, 2x300mL) . The CH 2 C1 2 extract was washed with IL brine, dried (MgSO * ) , and evaporated. The yellow oily residue was chromatographed ' on silica, eluting with CH 2 C1 2 - petroleum ether (1:5 to 1:4) .3g (100% yield) of yellow solid, [ α] (c=0.39. C 6 H 6 } ' λ E NMR (200 MHz, CDC1 3 ) : δ :8.0-6.5 (m, 19.4H) , 5.45 (br dd, 2.16H), 3.6-2.8 (m, 3.69H), 2.8-2.5 (m, 1.84H) , 2.3-1.9 (m, 1.90H), 1.1-0.9 (3 singlets, 16.5H) , 0.3- 0.15 (m, 10.3H). IR (KBr, cm "1 ): 2955, 2928, 2889, 2855, 1420, 1461, 1360, 1252, 1105, 1051, 1037, 985, 955, 884, 861, 836, 777755., EXAMPLE IQ (S,S)-(-)-JI (200mg) and 150mg iodine dissolved in 440mL benzene (Fisher, spectra-analyzed) was degassed with argon for 20min and 5mL propylene oxide was added. The solution was then irradiated for 12h through a water- cooled pyrex jacket by means of a Hanovia medium pressure Hg lamp. The solvent was evaporated. This experiment was repeated ten times, and the combined residues, dissolved in CH 2 Cl 2 -petroleum ether (1:1), were filtered through a 4" column of neutral alumina. Evaporation gave an orange solid, which was taken up in lOOmL dry THF in a 250mL round-bottomed flask and cooled to -78°C under Ar. t-Butyllithium in pentane (lOmL, 1.7M) was added, and after the dark mixture had stirred at -78°C for 20min, it was quenched with water and allowed to warm to room temperature. Extraction into lOOmL ether, washing with brine, drying (MgS0 4 ) , and evaporation gave a yellow-orange solid, which was dissolved in benzene (lOOmL) containing p-toluene- sulfonic acid monohydrate (50mg) . The solution was refluxed for 30min, cooled, extracted with lOOmL ether, washed with saturated NaHC0 3 solution (50mL) and brine (50mL), dried (MgS0 4 ) ■ and evaporated giving an oily solid. Chromatography on alumina (silica can also be used) and elution with CH 2 Cl 2 -petroleum ether (1:10 to 1:5) gave 635mg (56%) of £ as a yellow solid, [α ] 5 „ ?8 o 20 -3■_,4,8„0*,° C * H0 2 ,CV~1L 2 ,).. 1 H NMR (200MHz, CDC1 3 ) δ : 7.99 (2, 2H) , 7.93 (d, J=8.2Hz, 2H) , 7.69 (d, J*8.2Hz, 2H) , 7.21 (an AB quar¬ tet, J=8.6Hz, 4H) , 7.13 (an AB quartet, J=8.0Hz, 4H) - 6.45 (dt, J=5.5, 1.8Hz, 2H) , 5.82 (dt, J=5.5, 1.9Hz, 2H), 1.91 (dt, J»23.8,- 1.7Hz, 2H) , 1.03 (dt, J=23.6, 1.7-2.0HZ, 2H) . IR (KBr, cm "1 ): 3033(m), 2923(w), 1609(w) , 1385(m) , 1321(m), 1254(m), 1196(w), 1160(w) , 953(m), 839(vs) , 775(m), 697(s), 675(m), 637(m) , 566(s), 504(m), 403(w) . EXAMPLE 11 M-(-)-J (150mg, [ ] 5Q9 =-3480 o ) was dissolved under argon in lOmL dry THF in a lOOmL round-bottomed flask, the solution was cooled to -78°C, and lmL 1.6M t-butyl- lithium was added. The deep brown mixture was stirred at 0°C for 90min, cooled to -78°C, and then 105mg CoBr 2 .DME complex was quickly added against an argon stream. The solution was stirred at room temperature for 2h and then cooled to -78°. Another 120mg CoBr 2 .DME was then added. The mixture was stirred at room temperature for 7h. It was then quenched at 0°C with a solution of 0.5mL cone. HC1 in 5mL water. After stirring 2min, 300mg ferric chloride hexahydrate (Fish- er) was added, and the mixture was stirred overnight. The deep red almost transparent solution was diluted with THF, filtered through celite, and the celite pad was washed with moist acetone. The filtrate was evapo¬ rated and the residue washed with ether (3x50mL, the washings being discarded) . The solid was dissolved in acetone-water and after 600mg NH 4 PFg in acetone (5mL) was added, the solution was concentrated and the pre¬ cipitate filtered. Washing this precipitate with much water (lOOmL) and ether, and drying at 0.005mmHg gave 150mg (69%) brick-red solid, [ α ] 578 20 =-20,300° (c=0.0012, acetone). Purification was achieved by adding a filtered solution of this material in acetone to vigorously stirred anhydrous ether and filtering the precipitate. The optical rotation of purified material was almost the same: [ ά ] 578 20 =-20,400 to 20,800°. IR (KBr, cm "1 ) . 3658(m) and 3585 (m, water peaks), 3115(m), 3040(m), 1699(w), 1602(s), 1495(w), 1430(w), 1385 (m), 1302 (w), 1245(w), 1203(w), 1167(w), 841(vs), 783 (m), 731 (m) , 680 (w) , 646(w), 603(w), 558(vs), 472 (m) , 396 (w) . A H NMR (300MHz, CD 3 COCD 3 ) : 8.3-61 (br m, 14H) , 6.1- 5.4 (br m, 2H) , 5.1-3.9 (br m, 4H) . Elemental analysis: Calculated for ( 36 H 20 oPE n ' 65.85; H,3.07; Co, 8.98; P, 4.73; F, 17.38 found C, 71.24; H, 3.90; Co, 6.72; F, ; calculated for (C 36 H 21 C0PFg) (C 36 H 20 CoPFg) 2 (C 3 gH 21 ) : C, 71.35; H, 3.41; Co, 7.65. Rgferences 1. Katz, T.J.; Slusarek, W. J. Am. Chem. Soc. , 1Q : 4259, (1979) 2. (a) Katz, T.J.; Schulman, J. J. Am. Chem. Soc. 2& 3169, (1964). (b) Katz, T.J.; Balogh, V.; Schulman, J. Xbϋ^ , £_Q_: 734, (1968) . 3. (a) Katz, T.J.; Pesti, J. J. Are. Chem. Soc. ifli: 346, (1982). (b) Pesti, J. Ph.D. Dissertation, Columbia University, New York, N.Y. , (1981). 4. (a) Carraher Jr., C.E.; Sheats, J.E.; Pittman Jr., CU. "Organometallic Polymers," Academic Press: New York, (1978). (b) Hagihara, N.; Sonogashira, K.; Takahashi, S. Adv. Poly . Sci. 4.: 149, (1981) . 5. Martin observed a similar effect [Martin, R.H.; Schurter, J.J. Tetrahedron 2£: 749, (1972). 6. (a) Martin, R.H. Tetrahedron 20: 897, (1964). (b) Martin, R.H.; Defay, N.; Geerts-Evard, F.; Delavarenne, S. Ibid. 21: 1073, (1964) . 7. Sudhakar, A. Ph.D. Dissertation, Columbia Univer¬ sity, New York, N.Y.. 1985. 8. Kolle, U.; Khouzami, F. Chem. B r. 114: 2929, (1981) . 9. See Treichel, P.M.; Johnson, J.W.; Calabrese, J.C. Jt Qrganpmet. Chem. - 215, (1975). 10. Defay, N.; Zimmermann, D.; Martin, R.H. Tetrahe¬ dron Lett. P. 1871 (1971). 11. Kohler, F.H. Chem. Ber. 107: 570, (1974). 12. B.M. Trost, Chem. Soc. Rev, page 141, (1982) and references cited therein. 13. Koreeda et al., J. Orσ. Chem.. 43: 1023, (1978). 14. (a) Nesmeyanov, A.N. et al. Izv. Akad. Nauk SSSR, Ser. Khim. 667, (1963). (b) Watanabe, H., Motoyama, I.; Hata, K. Bull. Chem. Soc. Jpn. 3_£: 790, (1966). (c) Roling, P.V.; Rausch, M.D. J. Org. Chem. H: 729, (1972). (d) Izumi T.; Kasahara, A. Bull. Chem Soc. Jpn. ££: 1955, (1975). (e) Bednarik, L.; Gohdes, R.C.; Neuse, E.W. Transition-Met. Chem. 2: 212, (1977). 15. Metallocene polymers and their conductivities are discussed in (a) Neuse, E.W.; Rosenberg, H. Rev. Macro ol. Chem., Part 1, 5., (1970). (b) Lorkowski, H. - J. Fortschr. Chem. Forsch. 9/2: 207, (1967). 16. (a) Bilow, N.; Landis, A.L.; Rosenberg, H.J. Polym. Sci., Part A-l ∑: 2719, (1969). (b) Neuse, E.W.; Crossland, R.K. J. Organomet Chem. 2: 344, (1967).

Claims: hat is claimed, is 1. A helicene compound having the structure; which contains seven six-membered conjugated aro¬ matic rings capped by two five-membered rings which do not superimpose on each other. A helical metallocene oligomer capped by unsatura¬ ted five-membered rings, having the structure: wherein M is a transition metal halide and n=l to 100. 3. The oligomer of claim 2, wherein the oligomer is in optically active form. 4. The oligomer of claim 2, wherein the path of con¬ jugation of electrons extending from one metal to the next is unbroken either by atoms that do not have available a single TΓ electron to contin¬ ue the path of conjugation or in which the carbon skeleton does not constrain the π electrons on adjacent atoms to almost parallel orbitals. 5. The oligomer of claim 2, wherein the halide bound to the transition metal is in the form of a hexa- halophosphate. 6. The oligomer of claim 2, wherein the transition metal halide is cobalt hexafluorophosphate. 7. The oligomer of claim 2, which is useful as a conductor of electricity. 8. The oligomer of claim 2, which has magnetic prop¬ erties. 9. The oligomer of claim 2, which has optical proper¬ ties. 10. The oligomer of claim 2, which is useful as a catalyst in inducing asymmetry in chemical transformations. 11. A method of preparing the helicene of claim 1 which comprises: a) contacting a compound having the structure •i o wherein R«(t-Bu)Me 2 Si, with 1,4 -bis- [(CgH 5 ) 3 P + CH 2 ]-2-Br-CgH 3 , under suitable con¬ ditions to form a compound having the struc¬ ture: b) subjecting the compound formed in step (a) to light energy in the presence of an acid scav- enger compound which results in a photocycli¬ zation; and c) contacting the cyclized product of step (b) with a suitable reducing agent and an acid to form the helicene of claim 1. 12. The method of claim 11, wherein the acid scavenger of step (b) is propylene oxide. 13. A method of preparing the oligomer of claim 2 which comprises: a) contacting the helicene of claim 1 with a suitable base; b) contacting the product resulting from step (a) with a transition metal halide in a suitable solvent; c) contacting the product of step (b) with a suitable oxidizing agent; and d) contacting the product of step (c) with a hexahalophosphate salt to produce the oligomer of claim 2. 14. The method of claim 13, wherein the base of step (a) is t-butyllithium. 15. The method of claim 13, wherein the transition metal halide is cobalt dibromide. 16. The method of claim 13, wherein the oxidizing agent of step (c) is iron trichloride. 17. The method of claim 13, wherein the hexahalophos¬ phate salt is NH 4 PFg. 18. A metallocene oligomer having the structure: wherein M is a metal or salt thereof selected from the transition elements, the lanthanides or actinides, n»l to 100, and wherein the path of conjugation extending from one metal to the next is unbroken. 19. An optically active oligomer of claim 18. 20. An oligomer of claim 18 which has a helical structure. 21. An oligomer of claim 19 which has a helical structure. 22. The method of claim 11 wherein the reducing agent of step (c) removes the Br group and the acid of step (c) eliminates the RO-groups to introduce two double bonds. 23. The method of claim 13 wherein the hexahalophosphate of step (d) substitutes for the transition metal halide.

Inventors: KATZ THOMAS J, SUDHAKAR ANANTHA, KATZ, THOMAS, J., SUDHAKAR, ANANTHA
Applicants: UNIV COLUMBIA, THE TRUSTEES OF COLUMBIA UNIVERSITY IN THE CITY OF
Application year: 1986
Main classification: C07F11
IPC codes: C07C13, C07C45, C07F7, C07F15, C07F17