Photoinduzierte 1, 3-dipolare Cycloaddition von 3-Phenyl-2H-azirinen an Azodicarbonsäure-diäthylester. 32. Mitteilung über Photoreaktionen

Irradiation of 2, 2-dimethyl-3-phenyl- ( 1a ), 2, 3-diphenyl-2H-azirine ( 1b ) or the azirine-precursors 1-azido-1-phenyl-propene ( 2a ) and 1-azido-1-phenyl-ethylene ( 2b ), respectively, in benzene in the presence of azodicarboxylic acid diethylester, yields the corresponding 1, 2-carbethoxy-3-phenyl-Δ³-1, 2, 4-triazolines 4a–d (Scheme 1). Refluxing 4 ( a, c or d ) in 0, 2–0, 4M aqueous ethanolic potassium hydroxide leads to the formation of the 1-carbethoxy-3-phenyl-Δ²-1, 2, 4-triazolines 6 ( a, c or d ). Under the same conditions 4b is converted to 3, 5-diphenyl-1, 2, 4-triazole ( 7b , Scheme 2). In 10M aqueous potassium hydroxide solution heating of either 4 ( c or d ) or 6 ( c or d ) yields the 3-phenyl-1, 2, 4-triazoles 7 ( c or d ). Photolysis of 1-carbethoxy-5, 5-dimethyl-3-phenyl-Δ²-1, 2, 4-triazoline ( 6a ) in benzene in the presence of oxygen and trifluoroacetic acid methylester gives the 5-methoxy-2, 2-dimethyl-4-phenyl-5-trifluoromethyl-3-oxazoline ( 13 , Scheme 5). 5, 5-Dimethyl-3-phenyl-1, 2, 4-triazole seems to be the intermediate, which on losing nitrogen gives the benzonitrile-isopropylide ( 3a ).     

Studies on the synthesis of heterocyclic compounds. Part VI. The action of methyl salicylate on some 5-aminopyrazoles

Some 1-phenyl-3-R-5-aminopyrazoles reacted with methyl salicylate to give N-(1-phenyl-3-R-pyrazol-5-yl)-2-methoxybenzamides ( 3a,b,c ), 1-phenyl-2-methyl-3-R-salicyloilimino-3-pyrazolines ( 4a,b,c ) together with 1-phenyl-3-R-5-methylamino pyrazoles ( 5a,b,c ). The structures of the new compounds 3 and 4 were determined on the basis of analytical and spectroscopic data as well as on the acid hydrolysis products.     

Photochemical Reactions. Part 64 [1]. The photochemistry of 3-alkyl-cyclopent-2-en-ones

On ultraviolet irradiation in toluene, cyclopent-2-en-one ( 1a ) and 3-methylcyclopent-2-en-one ( 1b ) undergo dimerisation (→ 3a, b, 4b ), whereas 3-t-butyl-cyclopent-2-en-one ( 1e ) and the bicyclo [3.2.1]octenone 2a only react with the solvent (→ 5e–7e, 8–10 ). The 3-ethyl-( 1c ) and 3-isopropyl-cyclopent-2-en-ones ( 1d ) afford by dimerisation products 3c, d, 4c and by reaction with the solvent 5c, d, 6c, d, 7d . The β-methoxy-enones 1f and 2b are unreactive under comparable irradiation conditions. The head-to-head cyclobutane dimer 3b (HH) by separate irradiation at < 3400 Å in toluene, is reconverted to 1b . By similar irradiation each of the head-to-tail dimers 3b (anti- and syn-HT) and also the unsaturated dimer 4b give a new isomer of unknown structure besides small amounts of monomer 1b and relatively large amounts of insoluble material. The photoreactions of 1b-e can be quenched by naphthalene. Stern-Volmer plots for the quenching of the dimers of 1b, 1c , and 1d , and of 3-t-butylcyclopentanone ( 5e ) and the dihydro dimer 7e are linear and within each experiment, the slopes satisfactorily coincide, whereas the slope for the α-benzyl ketone 6c is distinctly greater than that for the dimers 3c . A similar differentiation, although less pronounced, is found between the benzyl ketones 6d and 6e and the respective accompanying products.     

Thermische Lactonisierung von Estern γ-Brom-α, β-ungesättigter Carbonsäuren zu Δα-Butenoliden. Direkte γ-Bromierung von α, β-ungesättigten Säuren

By heating with iron powder at 120–150° some γ-bromo-α, β-unsaturated carboxylic methyl esters, and, less smothly, the corresponding acids, were lactonized to Δ^7alpha;-butenolides with elimination of methyl bromide. The following conversions have thus been made: methyl γ-bromocrotonate ( 1c ) and the corresponding acid ( 1d ) to Δ^α-butenolide ( 8a ), methyl γ-bromotiglate ( 3c ) and the corresponding acid ( 3d ) to α-methyl-Δ^α-butenolide ( 8b ), a mixture of methyl trans- and cis-γ-bromosenecioate ( 7c and 7e ) and a mixture of the corresponding acids ( 7d and 7f ) to β-methyl-Δ^α-butenolide ( 8c ). The procedure did not work with methyl trans-γ-bromo-Δ^α-pentenoate ( 5c ) nor with its acid ( 5d ). Most of the γ-bromo-α, β-unsaturated carboxylic esters ( 1c, 7c, 7e and 5c ) are available by direct N-bromosuccinimide bromination of the α, β-unsaturated esters 1a, 7a and 5a ; methyl γ-bromotiglate ( 3c ) is obtained from both methyl tiglate ( 3a ) and methyl angelate ( 4a ), but has to be separated from a structural isomer. The γ-bromo-α, β-unsaturated esters are shown by NMR. to have the indicated configurations which are independent of the configuration of the α, β-unsaturated esters used; the bromination always leads to the more stable configuration, usually the one with the bromine-carrying carbon anti to the carboxylic ester group; an exception is methyl γ-bromo-senecioate, for which the two isomers (cis, 7e , and trans, 7d ) have about the same stability. The N-bromosuccinimide bromination of the α,β-unsaturated carboxylic acids 1b , 3b , 4b , 5b and 7b is shown to give results entirely analogous to those with the corresponding esters. In this way γ-bromocrotonic acid ( 1 d ), γ-bromotiglic acid ( 3 d ), trans- and cis-γ-bromosenecioic acid ( 7d and 7f ) as well as trans-γ-bromo-Δ^α-pentenoic acid ( 5d ) have been prepared. Iron powder seems to catalyze the lactonization by facilitating both the elimination of methyl bromide (or, less smoothly, hydrogen bromide) and the rotation about the double bond. α-Methyl-Δ^α-butenolide ( 8b ) was converted to 1-benzyl-( 9a ), 1-cyclohexyl-( 9b ), and 1-(4′-picoly1)-3-methyl-Δ^α-pyrrolin-2-one ( 9 c ) by heating at 180° with benzylamine, cyclohexylamine, and 4-picolylamine. The butenolide 8b showed cytostatic and even cytocidal activity; in preliminary tests, no carcinogenicity was observed. Both 8b and 9c exhibited little toxicity.     

Furopyridines. VII. Preparation and hydrolysis of 2-cyano and 3-cyano derivatives of furo[3,2-b]-, furo[2,3-c]- and furo[3,2-c]pyridine

This paper describes the preparation and hydrolysis of 2-cyano and 3-cyano derivatives of furo[3,2-b]-, furo[2,3-c]- and furo[3,2-c]pyridine. Treatment of furopyridines 1a , 1b and 1c with n-butyllithium in hexane-tetrahydrofuran at -70° and subsequent addition of N,N-dimethylformamide yielded 2-formyl derivatives 2a , 2b and 2c. Dehydration of the oximes 4a , 4b and 4c of 2a , 2b and 2c gave 2-cyano compounds 5a , 5b and 5c , which were hydrolyzed to give 2-carboxylic acids, 6a, 6b and 6c , respectively. Reaction of 3-bromo compounds 7a , 7b and 7c with copper(I) cyanide in N,N-dimethylformamide afforded 3-cyano derivatives 8a , 8b and 8c. Alkaline hydrolysis of 8a , 8b and 8c gave compounds formed by fission of the 1-2 bond of furopyridines 9a , 9b and 9c , while acidic hydrolysis gave the corresponding carboxamides, 10a , 10b and 10c.     

Reaction of ethyl 3-ethoxymethylene-2,4-dioxovalerate and ethyl ethoxymethyleneoxaloacetate with 3-aminopyrazole analogs. Synthesis and chemistry of 3,6,7-trisubstituted pyrazolo[1,5-a]pyrimidine derivatives

The chemical reactivity of a series of 3-substituted-6-acetyl-7-carbethoxypyrazolo[l,5-a]pyrimidines ( 6a,b,c ) and 3-substituted-6,7-dicarbethoxypyrazolo[1,5-a]pyrimidines ( 7a,b,c ), prepared by the condensations of the 3-aminopyrazole analogs ( 3a,b,c ) with ethyl 3-ethoxymethylene-2,4-dioxovalerate ( 1 ) or ethyl 3-ethoxymethyleneoxaloacetate ( 2 ), was investigated. Catalytic hydrogenation of 6 or 7 afforded 4,7-dihydro derivatives ( 8 or 9 ). Treatment of 6a,b with acetic acid and water underwent ring transformation into 6H-pyrazolo[1,5-a][1,3]diazepin-6-ones ( 17a,b ). By treatment with phenylhydrazine compounds of type 6 underwent cyclization to yield 2H-dipyrazolo[1,5-a:4′,3′-e]pyrimidines ( 18a,b,c ). Compounds 6 or 7 were treated with an excess of diazomethane at room temperature to give 5-methyl-6H-cyclopropa[5a,6a]pyrazolo-[1,5-a]pyrimidines ( 24 and 25 ) in excellent yields. However, when this reaction was carried out under ice cooling, only compounds of type 23 were isolated. Reaction of 6a with ethyl diazoacetate is also described.     

Synthesis and stereochemistry of new trihydrodiazabicyclo-[3.m.n]alkano[4′,5′:1,2]pyrido[3,4-b]indole ring system

The classical Pictet-Spengler reaction of tryptamine with the isomeric N-benzylpiperidones 3a, 3b and N-benzylpyrrolidone 3c yielded the spiro derivatives of 1,2,3,4-tetrahydro-β-carboline 5a, 5b and 5c . Cyclocon-densation of the spirotetrahydrocarboline with chloroacetic chloride and the subsequent reductive debenzylation afforded the new ring systems of trihydrodiazabicyclo[3.m.n]alkano[4′,5′:1,2]pyrido[3,4-b]indoles 8a , 8b , and 8c . The structures of the bicyclic systems 8a, 8b , and 8c were determined by using both, high-resolution ¹H and ¹³C nmr techniques and force field and MNDO calculations.     

Synthese und IR.-spektroskopische Identifizierung epimerer 3-Äthinyl-5 α-cholestan-3-ole

Synthesis and IR. Spectroscopic Identification of Epimeric 3-Ethinyl-5α-cholestan-3-ols The syntheses of the 3β-ethinyl-5α-cholestan-3α-ols 2a, 2b, 2c and of the corresponding epimeric 3α-ethinyl-5 α-cholestan-3 β-ols 3a, 3b, 3c are described. Bands at 1000 cm^?1 for the α-alcohols and at 1030 cm^?1 for the β-alcohols are found to be useful for the IR. spectroscopic identification of epimeric 3-ethinyl-5α-cholestan-3-ols.     

Hetero-Diels-Alder cycloadditions of α,β-unsaturated acyl cyanides. Part 2. Reactions with N,N-dimethyluracils,a new route to 5-substituted uracil derivatives

The [4 + 2] cycloadditions of 2-oxobut-3-enenitrile ( 1a ), 2-oxopent-3-enenitrile ( 1b ), and ethyl 4-cyano-4-oxobut-2-enoate ( 1c ) with 1,3-dimethyluracil ( 2 ), 1,3, 6-trimethyluracil ( 9 ), or 1,3,5-trimethyluracil ( 16 ) were investigated. The reactions of 1a with 2 or with 9 lead to bicyclic adducts 3 and 10 , respectively. These hexahydro-cis-pyranopyrimidines undergo ring opening under acidic conditions, restoring in 4 and 11 , respectively, an uracil system comprising 2-hydroxybut-2-enenitrile as a side chain at C(5). The surprisingly stable enols tautomerize slowly to the corresponding acyl cyanides 6a and 13a , respectively. Reacting 1b or 1c with 2 and with 9 does not afford cycloadducts; instead the uracil derivatives 6b, c and 13b, c , respectively, show up, carrying at C(5) α-oxobutanenitrile side chains. Cleavage of the acyl cyanide functions in 6a–c and 13a–c with nucleophilic agents produces various acids, esters, or amides, i.e. derivatives 8a–c and 15–c , respectively. The methyl esters 8a (X ? MeO, R ? H) and 15a (X ? MeO, R ? H) are also formed directly from the adducts 3 and 10 , respectively, with acid or base catalysis in presence of MeOH. The cycloadducts 17a and 17c , resulting from the reaction of 1a and 1c with 16 , respectively, have a Me group at the ring junction C(4a) and are stable. The structure of 17c proves that this hetero-Diels-Alder addition of inverse electron demand follows the endo-mode.     

Photochemische Cycloadditionen von 3-Phenyl-2H-azirinen mit Benzoyl-, Äthoxycarbonyl- und Vinylphosphonaten 34. Mitteilung über Photoreaktionen

The irradiation of the 3-phenyl-2H-azirines 1a–c in the presence of diethyl benzoylphosphonate ( 8 ) in cyclonexane solution, using a mercury high pressure lamp (pyrex filter), yields the diethyl (4, 5-diphenyl-3-oxazolin-5-yl)-phosphonates 9a–c (Scheme 3). In the case of 1b a mixture of two diastereomeric 3-oxazolines, resulting from a regiospecific but non-stereospecific cycloaddition of the benzonitrile-benzylide dipole 2b to the carbonyl group of the phosphonate 8 , was isolated. Benzonitrile-isopropylide ( 2a ), generated from 2,2-dimethyl-3-phenyl-2H-azirine ( 1a ), undergoes a cycloaddition reaction to the ester-carbonyl group of diethyl ethoxycarbonylphosphonate ( 15 ) with the same regiospecificity to give the 3-oxazoline derivative 16 (Scheme 5). The azirines 1a–c , on irradiation in benzene in the presence of diethyl vinylphosphonate ( 17 ) give non-regiospecifically the Δ¹-pyrrolines 13a–c and 14a–c (Scheme 6).     

Preparation of 3-bromo-2-methylfuran and 4-bromo-2-methylfuran

4-endo-5-exo-Dibromo-3-methyl-3,6-endo-oxyperhydrophthalic anhydride 3b and 4-exo-5-endo-dibro-mo-3-methyl-3,6-endo-oxyperhydrophtbalic anhydride 3c were isolated from the bromo-adducts of 3-methyl-3,6-endo-oxy-1,2,3,6-tetrahydrophthalic anhydride 2. When 3b or 3c was heated in quinoline, only 3-bromo-2-methylfuran 4 was obtained from 3b and only 4-bromo-2-methylfuran 5 from 3c.     

Photochemische Cycloadditionen von 3-Phenyl-2H-azirinen an Carbonsäurechloride. 35. Mitteilung über Photoreaktionen

Irradiation of 2, 3-diphenyl-2H-azirine ( 1a ) and 1-azido-1-phenyl-propene, the precursor of 2-methyl-3-phenyl-2H-azirine ( 1b ), in benzene, with a high pressure mercury lamp (pyrex filter) in the presence of acid chlorides yields the oxazoles 5a–d (Scheme 2). Photolysis of 2, 2-dimethyl-3-phenyl-2H-azirine ( 1c ) under the same conditions gives after methanolysis the 5-methoxy-2, 2-dimethyl-4-phenyl-3-oxazolines 7a, b, d , while hydrolysis of the reaction mixture leads to the formation of the 1, 2-diketones 8a, c, d (Scheme 4). The suggested reaction path for all these reactions is a 1, 3-dipolar cycloaddition of the photochemically generated benzonitrilemethylides 2 to the carbonyl double bond of the acid chlorides to give the intermediates 4 , followed by either elimination of hydrogen chloride or solvolysis (Schemes 2 and 4). Irradiation of 1c in the presence of acetic acid anhydride leads via the intermediate 9 to the 5-hydroxy-3-oxazoline 10 and the 5-methylidene-3-oxazoline 11 (Scheme 5).     

Saturated heterocycles. Part 216 . Synthesis,structure and ring opening of trans-perhydro-1,4-benzoxazepin-3-one derivatives

trans-Perhydro-1,4-benzoxazepin-3-ones 2a-c were synthesized and transformed to condensed-skeleton perhydro-trans-1,4-benzoxazepines 3a,b , the thiones 4a,b , the urea derivatives 5a,b , and N-acylated compounds 6a-e . Compounds 6b,d were ring-opened by hydrochloric acid in ethanol to yield trans-2-(1-carbethoxyethoxy)-1-acylaminomethylcyclohexane derivatives 7b,d . The ¹H- and ¹³C-nmr investigation and X-ray analysis of 5b and 6c,d proved that the expected N-acylated derivatives were formed and that both rings of the trans anellated compounds have a chair conformation.     

Furopyridines. XXIV. Nitration,chlorination, acetoxylation and cyanation of 2,3-dihydrofuro[2,3-b]-, -[3,2-b]-, -[2,3-c]- and -[3,2-c]pyridine N-Oxides

Nitration of 2,3-dihydrofuro[3,2-b]- N-oxide 3b and -[2,3-c]pyridine N-oxide 3c afforded the nitropyridine compounds 4b, 5b and 6 from 3b and 4c, 5c, 5′c and 7 from 3c , while -[2,3-b]- N-oxide 3a and -[3,2-c]pyridine N-oxide 3d did not give the nitro compound. Chlorination of 3b and 3c with phosphorus oxychloride yielded mainly the chloropyridine derivatives 15b, 15′b from 3b and 15c and 15′c from 3c , whereas 3a and 3d gave pyridine derivatives formed through fission of the 1–2 ether bond of the furo-pyridines 13a , 14 and 13d . Acetoxylation of 3b and 3c gave 3-acetoxy derivatives 18b and 18c and the parent compound 1b and 1c . Acetoxylation of 3a yielded compounds formed through fission of the 1–2 bond 16 and 17 and 3d gave furopyridones 19 and 19 ′. Cyanation of 3b and 3c yielded mainly the cyanopyridine compounds 20b, 20c and 20′c . Cyanation of 3a and 3d gave the cyanopyridine compounds 20a , 20d and 20′d accompanying formation of the pyridine derivatives 21a, 21d and 21′d .     

New beta-lactam antibiotics. Cephem derivatives with electron withdrawing substituents at position 3 (author's transl)]

New β-lactam antibiotics. Cephem derivatives with electron withdrawing substituents at position 3 Oxidation of the 3-formyl-2-cephem compound 1 according to Corey [6] gave 2-cephem-3-carboxylic esters 4a, b, c (Scheme 1), which proved to be useful intermediates for the synthesis of cephalosporins bearing in position 3 a methoxycarbonyl group (10a, b, c, d / Scheme 2) or a carboxy group (20, 25, 30/Schemes 3, 4). The 3-formyl-3-cephem compounds 31a, b could be transformed into cyano- (33a) or methoxyiminomethyl- (36a, c, d) cephems (Scheme 5), which represent further examples of cephalosporins with electron withdrawing groups in position 3.     

The formation of 3‐ferrocenylpyrazole‐4‐carboxylates and alkylhydrazine insertion products from α‐ferrocenylmethylidene‐β‐oxocarboxylates

The reactions of α‐ferrocenylmethylidene‐β‐oxocarboxylates ( 1 , 2 , 3a , and 3b ) with N‐methyl‐ and N‐(2‐hydroxyethyl)hydrazines ( 5a , 5b ) afford ethyl 1‐alkyl‐5‐aryl(methyl)‐3‐ferrocenylpyrazole‐4‐carboxylates ( 6a , 6b , 6c , 6d , 6e ) (～50%) and N‐alkylhydrazine insertion products, viz., ethyl (N′‐acyl‐N′‐alkylhydrazino)‐3‐ferrocenylpropanoates ( 7a , 7b , 7c , 7d , 7e ) (～20%) and 1‐acyl‐2‐(N′‐alkyl‐N′‐ethoxycarbonylhydrazino)‐2‐ferrocenylethanes ( 8a , 8b , 8c , 8d , 8e ) (～10%). The structures of the compounds obtained were established based on the spectroscopic data and X‐ray diffraction analysis (for pyrazoles 6a and 6b ). J. Heterocyclic Chem., (2011).     

Stereoselectivity of the Diels-Alder Reaction of (E)-γ-Oxo-α,β-Unsaturated Thioesters with Cyclopentadiene

The stereoselectivity of the Diels-Alder reaction of (E)-γ-oxo-α,β-unsaturated thioesters 3a-3d with cyclopentadiene is greatly enhanced in the presence of Lewis acids favoring the endo acyl isomers 4a-4d . In the absence of Lewis acid, Diels-Alder reaction of 3a-3d with cyclopentadiene at 25 °C gave two adducts 4a-4d and 5a-5d in a ratio of 1:1 respectively. In the presence of Lewis acids, Diels-Alder reaction of 3a-3d with cyclopentadiene gave 4a-4d and 5a-5d in ratios of 75-94:25-6 respectively. The stereoelectivity was enhanced to ratios of 95-98:5-2 with lowering the reaction temperature. The stereochemistry of the cycloadducts 4 and 5 was confirmed by iodocyclization. Reaction of the endo-thioester 5c with I₂ in aqueous THF at 0 °C gave the novel methylthio group rearranged product 6c in 80% yield, the first example of iodo-lactonization of endo-thioesters. Reaction of the endo-acyl isomer 4b with I₂ under the same reaction conditions gave an isomeric mixture of 7b and 8b in 1:2 ratio. The stereochemistry of the thioester group in 8b was proved by X-ray single-crystal analysis. The solvent effect on the endo selectivity of (Z)-γ-oxo-α,β-unsaturated thioester 2b was also examined.     

Synthesis and isolation of bromo‐β‐carbolines obtained by bromination of β‐carboline alkaloids

β‐Carbolines ( 1–5 ) undergo electrophilic aromatic substitution with N‐bromosuccinimide under different experimental conditions. Although 6‐bromo‐nor‐harmane ( la ) obtained by bromination of nor‐harmane ( 1 ) was isolated and fully characterized sometime ago, the other bromoderivatives of nor‐harmane ( 1b‐1e ) and harmane ( 2a‐2e ) were partially described as part of the reaction mixtures. The preparation and subsequent isolation, purification and full characterization of 1b, 1c, 1d, 1e, 2a, 2b, 2c, 2d, 2e are reported (mp, R _f, ¹H‐nmr, ¹³C‐nmr and ms) together with the preparation, isolation and charaterization, for the first time, of the bromoderivatives obtained from harmine ( 3a‐3e ), harmol ( 4a, 4b ) and 7‐acetylharmol ( 5a‐5c ). As brominating reagent N‐bromosuccinimide and N‐bromosuccinimide‐silica gel in dichloromethane and in chloroform as well as the β‐carboline ‐ N‐bomosuccinimide solid mixture have been used and their uses have been compared. Semiempirical AMI and PM3 calculations have been performed in order to predict reactivity in terms of the energies of HOMO, HOMO‐LUMO difference and in terms of the charge density of β‐carbolines ( 1–5 ) and bromo‐β‐carbolines ( 1a‐1e, 2a‐2e, 3a‐3e, 4a, 4b, 5a, 5b and 5c ) (Scheme 1). Theoretical and experimental results are discussed briefly.     

Furopyridines. IX. Syntheses and properties of 3-ethoxy derivatives of furo[2,3-b]-, furo[3,2-b]-, furo[2,3-c]- and furo[3,2-c]pyridine

Reaction of ethyl 3-ethoxycarbonylmethoxyfuropyridine-2-carboxylates 2a-2d with sodium ethoxide afforded 3-ethoxy derivatives 3a-3d which converted to 3-ethoxyfuropyridines 5a-5d by hydrolysis and decarboxylation of the ester group. Vilsmeier reaction of 5a and 5b gave 2-formyl-3-ethoxy derivatives 6a and 6b and 2-formyl-3-chloro derivatives 7a and 7b , while 5c and 5d did not give any formyl compound. Bromination of 3-ethoxyfuropyridines with 1 equivalent mole of bromine gave 2-bromo-3-ethoxyfuropyridines 9a-9d , whereas reaction with 3 equivalents of bromine yielded 2,2-dibromo-3,3-diethoxy-2,3-dihydrofuropyridines ( 10a and 10b ) and/or 2-bromo-3,3-diethoxy-2,3-dihydrofuropyridines 11b , 11c and 11d . Treatment of compounds 5a-5d with n-butyllithium in hexane-tetrahydrofuran at ?70° and subsequent addition of N,N-dimethylformamide yielded 2-formyl derivatives 6a-6d .     

The octant rule: XXIII. antioctant effects in γ,δ -unsaturated ketones.

The and -benzyl derivatives (1 and 2, respectively) of (+)-camphor have been synthesized and are found to exert a strong influence on the circular dichroism n→π^* Cotton effects: 1: Δε³⁰¹_max -0.36 (n- heptane) and 2: Δε³⁰²_max +3.22, relative to camphor: Δε³⁰⁴_max +1.8 (n-heptane). Evidence for electric dipole transition moment coupling in these γ, δ -unsaturated systems is found in the n→π^* UV: 1: ε²⁹¹_max 84 (n-heptane) and 2: ε²⁸⁵_max 303, relative to camphor: ε²⁹⁰_max 25.