New approach to the synthesis of 4,4-disubstituted cycloalkenones

Becker, D. Scott; Kalo, J.; Brodsky, Naphtali C.

doi:10.1021/jo00407a003

Cited by 9 publications

(2 citation statements)

References 2 publications

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“…During ketalization,46 9 is formed with simultaneous migration of the double bond, as has also been observed in other systems 47. It is known that substituents in the bicyclic systems can influence the location of the double bond in the formed ketal structure 48. The ketal product 9 was purified by fast column chromatography and characterized by spectroscopic analysis (one‐ and two‐dimensional NMR).…”

Section: Resultsmentioning

confidence: 73%

Photoreactions of Tricyclic α‐Cyclopropyl Ketones and Unsaturated Enones – Synthesis of Polyquinanes and Analogous Ring Systems

Tzvetkov¹,

Neumann²,

Stammler³

et al. 2006

Eur J Org Chem

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Polycyclic systems of both angular and propellane type have been synthesized through intramolecular radical cyclization reactions, by photochemically induced electron transfer of tricyclic α‐cyclopropyl ketones or by photolysis of unsaturated enones. In general, tricyclic α‐cyclopropyl ketones, each bearing an alkynyl or alkenyl side chain at the position γ to the carbonyl group, were used as starting materials. The reactions resulted in regioselective cleavage of one cyclopropyl bond with formation of tri‐ to tetracyclic ring systems by a tandem fragmentation‐radical/radical anionic reaction pathway. The regioselectivity of the cyclization (exo/endo) depends on the length of the unsaturated side chain. In cases involving α‐cyclopropane derivatives with alkoxymethyl side chains, various non‐cyclization processes were observed. In addition, the photoinduced cyclization of the corresponding bicyclic enone derivatives with the same unsaturated side chains afforded tetra‐ and tricyclic products of propellane type in good yields and with high stereoselectivity. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

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Section: Resultsmentioning

confidence: 73%

Photoreactions of Tricyclic α‐Cyclopropyl Ketones and Unsaturated Enones – Synthesis of Polyquinanes and Analogous Ring Systems

Tzvetkov¹,

Neumann²,

Stammler³

et al. 2006

Eur J Org Chem

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“…The significant shorter C9-C10 (1.328(5)Å)and C23-C24 (1.328(5) Å)bonds indicate the localization of the double bond of the five-membered ring. The simultaneous migration of the double bond during ketalization has also been observed in other systems and is best known phenomenon in the steroidal synthesis [4,5] …”

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confidence: 72%

Crystal structure of (7a'SR)-7a'-prop-2-ynyl-1',2',4',6',7',7a'- hexahydrospiro[1,3-dioxolan-2,5'-indene], C14H18O2

Tzvetkov¹,

Neumann²,

Stammler³

et al. 2006

Zeitschrift Für Kristallographie - New Crystal Structures

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Source of materialThe title compound has been obtainedbyketalization of (7aSR)-7a-prop-2-ynyl-1,2,3,6,7,7a-hexahydro-5H -inden-5-one with freshly distilled ethylene glycol in dry benzene under reflux over 6hand in the presence of p -toluenesulfonic acid monohydrate as an acid catalyst [1]. Purification of the crude product by column chromatography (cyclohexane/ethyl acetate,8 0:20) and recrystallization from chloroformand petroleum ether (1:2, v / v )gave the ketal product as colorless crystals suitable for X-ray structure analysis (m.p. 353-354 K, R f =0.49). DiscussionThe titlecompound was prepared as part of our study of diastereoselective cyclopropanization of centrosymmetricsubstituted indenones [2]. Wei ntroduced as eries of new tricyclic a -cyclopropyl indenone structures [3] as suitable intermediates in propellane synthesis. The racemicc ompound crystallizesc entrosymmetrically and the asymmetric unit contains two independentm olecules, which have no significant differences. The enantiomeric molecules show an antiparallel orientation. The significant shorter C9-C10 (1.328(5)Å)and C23-C24 (1.328(5) Å)bonds indicate the localization of the double bond of the five-membered ring. The simultaneous migration of the double bond during ketalization has also been observed in other systems and is best known phenomenon in the steroidal synthesis [4,5]

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Studies towards the Synthesis of (+)‐Dictyoxetane

Benford-Ward

Ahmadipour

Sembayeva

et al. 2022

Chemistry A European J

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The dolabellane‐type diterpene dictyoxetane represents a significant challenge to synthetic organic chemistry. Methodology directed towards the total synthesis of naturally occurring (+)‐dictyoxetane is reported. Catalytic asymmetric synthesis of the trans‐hydrindane ring system is achieved through chemoselective deoxygenation of the Hajos‐Parrish ketone. An alternative to the Garst‐Spencer furan annulation is developed for the synthesis of a 2,5‐dimethyl, tetrasubstituted furan, employing a tandem 5‐exo‐dig alcohol to alkyne cyclisation/aromatisation reaction as a key step. The (4+3) cycloaddition reaction of an oxyallyl cation with a tetrasubstituted furan is established on a cyclohexanone‐derived model system, and a range of related (4+3) cycloadditions investigated on a homochiral, trans‐hydrindane‐fused furan, where regio‐ and diastereoselectivity is required for the natural product synthesis. In an alternative (4+2) Diels‐Alder approach, a C2‐symmetric vinyl sulfoxide‐based chiral ketene equivalent is used to prepare oxanorbornenes with the same oxygen bridge stereochemistry found in the 2,7‐dioxatricyclo[4.2.1.03,8]nonane ring system of the natural product.

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New approach to the synthesis of 4,4-disubstituted cycloalkenones

Cited by 9 publications

References 2 publications

Photoreactions of Tricyclic α‐Cyclopropyl Ketones and Unsaturated Enones – Synthesis of Polyquinanes and Analogous Ring Systems

Photoreactions of Tricyclic α‐Cyclopropyl Ketones and Unsaturated Enones – Synthesis of Polyquinanes and Analogous Ring Systems

Crystal structure of (7a'SR)-7a'-prop-2-ynyl-1',2',4',6',7',7a'- hexahydrospiro[1,3-dioxolan-2,5'-indene], C14H18O2

Studies towards the Synthesis of (+)‐Dictyoxetane

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