Systematic structural modifications in the photochemistry of .beta.,.gamma.-unsaturated ketones. II. Acyclic olefins and acetylenes

Schexnayder, Mary A.; Engel, Paul S.

doi:10.1021/ja00850a008

Cited by 37 publications

(13 citation statements)

References 32 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…by Luis Schwager and Pierre Voge12) lnstitut de chimie organique de l'Universite, 2, rue de la Barre, CH-1005 Lausanne, Switzerland in toluene and (6.2k0.11). lo-' in benzene) only 60 times more slowly than 2,3-dimethylidenenorbornane (5) and ca. 850 times as fast as 2,3-dimethylidene-syn-l, 4,5,6-tetramethylbicyclo[2.1.1]hexane (9).…”

Section: The Synthesismentioning

confidence: 94%

“…A downfield shift effect of ca. 29 pprn is observed on the aC of the y-carbon atoms C (5,6) by introducing an endocyclic double bond in bicyclo [2.1. llhexane [23]. In contrast, 2-methylidenenorbornane [24] and 2,3-dimethylidene-norbornane [laa] [25] display a hc for C(7) very similar to that of norbornane.…”

Section: )mentioning

confidence: 99%

“…850 times more reactive than the syn-tetramethylated derivative 9 toward TCE. It appears, therefore, that steric hindrance to the approach of the dienophile due to the syn-methyl groups at C (5,6) in 9 might be a part of the Diels-Alder reactivity difference between the dienes 9 and 10. Nevertheless, we agree with Hogeveen et al [26] that steric hindrance alone cannot explain the observed difference in reactivity of these dienes.…”

Section: Diels-alder Reactivity Of 23-dimethylidene-bicyclo [2ll]hmentioning

confidence: 99%

See 2 more Smart Citations

The Photochemistry of 5,6‐Dimethylidene‐2‐norborananone. Synthesis and Diels‐Alder Reactivity of 2,3‐Dimethylidenebicyclo‐[2.1.1]hexane

Schwager

Vogel

1980

Helvetica Chimica Acta

View full text Add to dashboard Cite

2,3‐Dimethylidenebicyclo [2.1.1]hexane (4) was isolated from direct irradiation (253.7 nm) of 5,6‐dimethylidene‐2‐norbornanone (3). Quenching experiments at 253.7 nm, as well as direct and sensitized irradiations at >300 nm suggested that a high vibrationally excited S1‐ or a S2‐state is required for the photodecarbonylation of 3 in contrast with other β, γ‐unsaturated ketones for which α‐cleavage occurs with lower excitation‐energy. The new diene 4 reacted toward tetracyano‐ethylene (k 39.5°II (1mol−1 s−1))=(3.1±0.34) · 10−3) in toluene and (6.2±0.11) · 10−3 in benzene only 60 times more slowly than 2,3‐dimethylidenenorbornane (5) and ca. 850 times as fast as 2,3‐dimethylidene‐syn1,4,5,6‐tetramethylbicyclo[2.1.1]‐hexane (9).

show abstract

Section: The Synthesismentioning

confidence: 94%

Section: )mentioning

confidence: 99%

Section: Diels-alder Reactivity Of 23-dimethylidene-bicyclo [2ll]hmentioning

confidence: 99%

See 1 more Smart Citation

The Photochemistry of 5,6‐Dimethylidene‐2‐norborananone. Synthesis and Diels‐Alder Reactivity of 2,3‐Dimethylidenebicyclo‐[2.1.1]hexane

Schwager

Vogel

1980

Helvetica Chimica Acta

View full text Add to dashboard Cite

show abstract

“…30 HRMS (EI) calcd for C 11 H 8 O 2 I 299.96473, found: 299.96511. n-Butyl 2,2-dimethyl-3-butynoate (30). This compound was prepared by the esterification of 2,2-dimethylbut-3-ynoic acid 43 (0.05 mol), n-butanol (0.075 mol) and sulfuric acid (0.05 mol). The mixed solution was stirred at room temperature for 24 h. The resulting mixture was purified by flash chromatography on silica gel (10:1 hexanes/EtOAc) to afford compound 30 as a colorless oil in a 20% yield: 1 H NMR (CDCl 3 ) δ 0.93 (t, J = 7.5 Hz, 3H), 1.38-1.43 (m, 2H), 1.48 (s, 6H), 1.62-1.67 (m, 2H), 2.25 (s, 1H), 4.14 (t, J = 6.6 Hz, 2H); 13 C NMR (CDCl 3 ) δ 13.…”

Section: Generalmentioning

confidence: 99%

Synthesis of 2(3H)-furanones via electrophilic cyclization

Just

View full text Add to dashboard Cite

The electrophilic cyclization of functionally-substituted alkynes is a very promising route to an extraordinary range of medicinally-interesting, functionally-substituted heterocycles and carbocycles. A variety of highly substituted 2(3H)-furanones are readily prepared from 3-alkynoate esters and the corresponding acids via electrophilic cyclization. This highly efficient approach proceeds under mild conditions, tolerates various functional groups, and generally provides 2(3H)-furanones in good to excellent yields. The cyclizations of 3-alkynoate esters and the corresponding acids have been performed using an excess of the electrophile at room temperature using either methylene chloride or acetonitrile as the solvent. Successful electrophiles in this process include I 2 , ICl, and PhSeCl. The iodine functionality introduced into the heterocycle facilitates further elaboration by Pd-catalyzed chemistry. 1 GENERAL INTRODUCTION The electrophilic cyclization of functionally-substituted alkynes has proven to be a very promising route to an extraordinary range of medicinally-interesting, functionallysubstituted heterocycles and carbocycles. Previous work by our group and others has shown that iodine and other electrophiles can be used for the synthesis of benzo[b]furans, benzo[b]thiophenes, indoles, isoquinolines and a number of other heterocycles and carbocycles. This highly efficient approach to heterocycles and carbocycles proceeds under mild reaction conditions, accommodates various functional groups in the starting alkyne, and the iodo-substituted products can be further elaborated by Pd-catalyzed chemistry. Our interest in electrophilic cyclization has led us to further explore the generality of this approach for the synthesis of highly substituted 2(3H)-furanones. We have extensively studied the reaction of 3-alkynoate esters and the corresponding acids with various electrophiles and obtained highly substituted 2(3H)-furanones in fair to excellent yields. Dissertation Organization This thesis is composed of one main chapter. The chapter describes the synthesis of various 2(3H)-furanones from 3-alkynoate esters and the corresponding acids. The cyclization proceeds under relatively mild reaction conditions. Some 3-alkynoate esters give fair to good yields of 2(3H)-furanones, whereas other 3-alkynyl esters with more than one nucleophilic center failed to give the desired 2(3H)-furanones. The unsuccessful 3-alkynoate ester substrates can be easily transformed to the corresponding 3-alkynoic acids. These 3-alkynoic acids cyclize in the presence of various electrophiles to give fair to excellent

show abstract

“…* To whom correspondence should be addressed. 0108-2701/93/020338-03506.00 6-(3,3-Dimethyl-2-oxo-2,3-dihydro-5-furanyl)-2benzyloxypyridine (1), the precursor to (2), was prepared by stirring a mixture of 2-benzyloxy-6-bromopyridine (Duggan, Grabowski & Russ, 1980) (2.5 g, 0.01 mol), 2,2-dimethylbut-3-ynoic acid (Schexnayder & Engel, 1975) (1.13 g, 0.01 mol), dry triethylamine (15 mL), tetrakis(triphenylphosphine)palladium (0.35 g, 0.3 mmol) and copper(I) iodide (0.1 g, 0.5 mmol) in a sealed thick-walled pressure tube at 353 K, under an atmosphere of argon, for 5 h. The resultant cooled suspension was added to water (120 mL) and extracted with diethyl ether (2 x 70 mL). The combined ethereal extracts were dried (anhydrous magnesium sulfate) and evaporated in vacuo to a yellow oil (2.77g, 94%).…”

mentioning

confidence: 99%

Structure of 6-(3,3-dimethyl-2-oxo-2,3-dihydro-5-furanyl)-2-pyridone at 145 K

Maverick¹,

Chiefari²,

Lightner³

1993

Acta Crystallogr C

View full text Add to dashboard Cite

C11H11NO3, M(r) = 205.21, triclinic, P1, a = 5.725 (1), b = 9.038 (1), c = 10.401 (2) A, alpha = 101.37 (1), beta = 102.63 (1), gamma = 102.83 (1) degrees, V = 494.7 (3) A3, Z = 2, Dx = 1.38 g cm-3, lambda (Mo K alpha) = 1.7107 A, mu = 0.62 cm-1, F(000) = 216, T = 145 K, R = 0.049, wR = 0.063 for 2386 unique observed reflections. The molecules, which are self-associating in solution, are arranged in the crystal in centrosymmetric dimers joined by N--H...O bonds between the amide functional groups. Analysis of displacement parameters indicates that the furanyl and pyridone groups are independently quite rigid, with the furanyl group librating with respect to the hydrogen-bonded pyridone.

show abstract

Systematic structural modifications in the photochemistry of .beta.,.gamma.-unsaturated ketones. II. Acyclic olefins and acetylenes

Cited by 37 publications

References 32 publications

The Photochemistry of 5,6‐Dimethylidene‐2‐norborananone. Synthesis and Diels‐Alder Reactivity of 2,3‐Dimethylidenebicyclo‐[2.1.1]hexane

The Photochemistry of 5,6‐Dimethylidene‐2‐norborananone. Synthesis and Diels‐Alder Reactivity of 2,3‐Dimethylidenebicyclo‐[2.1.1]hexane

Synthesis of 2(3H)-furanones via electrophilic cyclization

Structure of 6-(3,3-dimethyl-2-oxo-2,3-dihydro-5-furanyl)-2-pyridone at 145 K

Contact Info

Product

Resources

About