Many-membered Carbon Rings. XIV. Transannular Ring Cleavage of Certain Cycloalkane Derivatives<sup>1</sup>

Blomquist, A. T.; Taussig, P. R.

doi:10.1021/ja01570a055

Cited by 27 publications

(6 citation statements)

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“…Alternatively, an acetylenic ene component is involved in the thermal conversion of (66) under similar conditions into the allene (67)[231. The quantitative transformation of dehydrolinalool (68) into (69)[33a1 proceeds at 200°C with AS*=-13.7 cal K-' mol-' and AH*=28.7 kcal mol-'['91 (showing a significantly lower free energy of activation than the analogous reaction of linalool (5)). The reaction (68)+ (69) has recently been in the synthesis of the spirosesquiterpene, 0-acoratriene (72).…”

Section: Genynes and 12gtrienesmentioning

confidence: 99%

Intramolecular Ene Reactions in Organic Synthesis

Oppolzer

Snieckus

1978

Angew. Chem. Int. Ed. Engl.

394

104

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Thermal cyclizations of appropriate dienes, enynes, enones and related unsaturated systems, some of them carried out on an industrial scale, demonstrate increasingly the preparative power of the intramolecular ene reaction. A variety of substituted, fused and bridged ring systems, including natural products, are thus easily accessible in a regio-and stereo-selective manner. Numerous examples are discussed systematically illustrating the possibilities. 11 initations, and common features of this cyclization reaction and its reverse ring-opening procw Scheme 1 . The intermolecular ene reaction.Early examples of the intramolecular ene reaction (Scheme 2) date back to the 1 9 3 0~~~-" 1 ; however, its synthetic utility has become recognized only recently parallel to the general interest in intramolecular [4 + 21" '-41 and [3 + 21" 4* ' ' I cycloadditions. Similar to the cycloadditions, the intramolecular ene process profits from entropic advantage and exhibits preparatively useful regio-and stereoselectivity. This applies to three different modes of thermally-induced cyclizations (and cycloreversions) (Scheme 2) in which the enophile is linked by an appropriate bridge, either to the olefinic terminal (Type I), the central atom (Type II), or the allylic terminal (Type 111) of the ene unit. 476

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Section: Genynes and 12gtrienesmentioning

confidence: 99%

Intramolecular Ene Reactions in Organic Synthesis

Oppolzer

Snieckus

1978

Angew. Chem. Int. Ed. Engl.

394

104

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“…The number of known examples of this retro-ene reaction in all carbon systems is small, and they require temperatures in the range of 250-580 °C.5 For example, m-cyclononene itself is converted into 1,8-nonadiene to the extent of only 20% at 500 °C. 6 The more facile rearrangement in the present case can be attributed to the formation of the aromatic ring.…”

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confidence: 58%

Annelation of 1,2-cyclononadiene with tetrachlorothiophene dioxide. An ene reaction with sulfur dioxide

Raasch¹,

Smart²

1979

J. Am. Chem. Soc.

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CH3O-+ CD3CN ^CH3OD + CD2CN-and subsequent exchange. Water can become strongly polarized, especially when occurring in small concentrations in aprotic solvents. This fact may be used to pump aqueous systems via a membrane together with a flow system.The molecules investigated here (Chart I) are models for those of biochemical interest, such as sugars, nucleic acids, etc.There CINOE might well be quite selective. Especially attractive seems the possibility of pumping 15N, where electronic pumps are inefficient because of the negative magnetic moment of l5N and the associated negative enhancement, which causes an initial signal loss. CINOE could provide a superior alternative for positive l5N signal enhancement. The above proton results seem encouraging. References and Notes(1) NATOAdv. Study Inst. Chem. Induced Magn. Polar., Ser. C34, 1977Ser. C34, , 1977 and references therein.(2) Intramolecular CINOE has been reported by: (a) Gloss, G. L; Czeropski,

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“…Treatment of the complex with the anion of diethyl malonate in the presence of triphenylphosphine led to essentially instantaneous reaction at room temperature to give a mixture of three isomers 10 (54%), 11 (34%), and (12%) in 68% yield after chromatographic purification. 4 The structural assignments are fully supported by spectral data. Thus, the alkylation introduces the new group with a preference for the less substituted end (9:1) of the -allyl system and placement of the alkylated chain cis to the 3-olefin alkyl group.…”

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confidence: 65%

“…Thus, alkylation of 6 with the anion of methyl methylsulfonylacetate gave a single crystalline, mp 78°, product 13 in 80% yield. 4 The stereochemistry was assigned cis by comparison of its nmr spectrum and its Eu(fod)s shifted nmr spectrum with that of the malonate product. In this case, the reaction proceeds completely regioselectively and stereoselectively!…”

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confidence: 99%

“…However, the sulfur stabilized anions successfully employed provide versatility for conversion to a wide range of different groups as eq 2,9 3,10 and 411 illustrate. 4 In these subsequent reactions, no attempt to optimize yields was made. Note that the transformation 2 -> 17 represents a homologation of a methyl group into an ethyl group (a process directly applicable for the important conversion of a farnesol derivative into a juvenile hormone derivative).…”

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confidence: 99%

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