A General Method for the Preparation of 2-Substituted and 2,3-Disubstituted Furans. A New Synthesis of Sesquirose Furan

Kotake, Hiroshi; Inomata, Katsuhiko; Kinoshita, Hideki; Aoyama, Shin-ichi; Sakamoto, Yoko

doi:10.3987/s-1978-01-0105

Cited by 25 publications

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“…4. [61][62][63][64][65][66][67][68] On the other hand, a number of methods for the preparation of pyrroles, which are five-membered heterocyclic compounds similar to furans, have been exploited, 69,70 because they are fundamental constituents of important substances, such as heme, chlorophyll, vitamin B 12 , and some of them have pharmacological activities themselves.…”

Section: Synthesis Of Bilin Chromophores Of Phytochromesmentioning

confidence: 99%

Studies on the Structure and Function of Phytochromes as Photoreceptors Based on Synthetic Organic Chemistry

Inomata

2008

Bulletin of the Chemical Society of Japan

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Section: Synthesis Of Bilin Chromophores Of Phytochromesmentioning

confidence: 99%

Studies on the Structure and Function of Phytochromes as Photoreceptors Based on Synthetic Organic Chemistry

Inomata

2008

Bulletin of the Chemical Society of Japan

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“…[1][2][3][4][5][6] Intrigued by a unique propensity of 2 to undergo facile elimination of a tosyl (Ts) group at the allylic position, we have also developed an alternative method for the preparation of allylic sulfones using Pd-catalyzed allylic substitution reaction as illustrated in Scheme 2. For example, allylic acetates 4 were readily converted to allylic sulfones 5 upon treatment with sodium p-toluenesulfinate in the presence of a catalytic amount of Pd(0) complex.…”

Section: Introductionmentioning

confidence: 99%

“…The predominant formation of Z-isomers in both cases was rationalized by the "syn-effect" based on the n/s p* interaction (58) and/or 6p-electron homoaromaticity. A similar consideration seems to be applicable to elucidate other related phenomena, 32 such as a favorable syn-conformation of esters (RCO 2 R'), as shown in Scheme 18 as an n p* interaction (59) with a sp 3 oxygen model for OR' instead of a usual n s* interaction (60) with a sp 2 oxygen model. …”

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confidence: 99%

"Syn-Effect" in the Base-Induced Isomerization of Vinylic Sulfones to Allylic Sulfones and the Related Various Reactions

Inomata

2009

J. Synth. Org. Chem. Jpn.

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: "Syn-effect" has been recognized as a major cause of stabilizing the syn-conformation at the transition state of a number of reactions against the steric hindrance. This account deals with the origin of the "syn-effect" on the basis of the stereochemical outcome in the isomerization of vinylic sulfones leading to the formation of allylic sulfones and in the related various reactions. We proposed that a s p* interaction between the s-orbital(s) of the allylic C-H s-bond(s) (or of the C-H s-bond(s) at the a-position for carbonyl compounds) and the antibonding orbital (p*) of the C=C double bond (or of the C=O double bond for carbonyl compounds) is the most important and essential factor for the "syn-effect", though the contribution of a 6p-electron homoaromaticity and/or of a hydrogen bonding cannot be entirely ruled out. Scheme 2fied (Scheme 3). 13Therefore, we started to prepare stereochemically well-defined vinylic sulfones and study the detailed stereochemistry of the isomerization. Consequently, we have found that (E)-vinylic sulfones preferentially provided sterically unfavorable (Z)-allylic sulfones, whose stereochemical course was explainable by so-called "syn-effect". Herein we will briefly introduce the stereochemical outcome in the isomerization of vinylic sulfones to allylic sulfones and in the related various reactions, and discuss the origin of this effect in detail. Regio--and Stereoselective Preparation of Vinylic SulfonesOur initial study focused on the stereoselective synthesis of (E)-and (Z)-vinylic sulfones 14, since the iodotosylation of 1-alkenes followed by triethylamine-induced dehydroiodination of the resulting 2-iodo-1-tosylalkanes 13 mostly provided a mixture of (E)-and (Z)-isomers of vinylic sulfones 14 as summarized in Scheme 4 and their separation into pure isomers turned out to be difficult. [14][15][16] Gratifyingly, 2-pyrrolidinyl-1-tosylalkanes 15 derived from 13 and an excess amount of pyrrolidine underwent a selective Cope elimination upon treatment of the crude products 15 with mCPBA in dichloromethane in the presence of Na 2 CO 3 to provide stereochemically pure (E)-vinylic sulfones (E)-14 in high yields (Scheme 5). 17 This procedure was much easier than an alternative method via a-phenylselenation of 1-tosylalkanes 16 and was applicable on a large scale.A possible key factor for success in the exclusive formation of (E)-14 may be the formation of 16 in favor of 17 in the transition state where the N-oxy-1-pyrrolidinyl group and the hydrogen should adopt eclipsed conformation, in order to avoid a severe steric congestion developed by an alkyl substituent R and the tosyl group (Ts) in 17 (Figure 2).The intermediary b-pyrrolidinylsulfones 15 were also used to prepare a-alkylated vinylic sulfones through a-alkylation followed by oxidative elimination of the pyrrolidinyl group. 15On the other hand, (Z)-14 were selectively synthesized in high yields by the Pd-catalyzed hydrogenation of (E)-2-iodo-1-tosyl-1-alkenes 18, which were prepared by the regio-and stereoselectiv...

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“…The vast majority of the published routes involve the chemical modification of acyclic precursors . These include, for example, the base-promoted cyclization of 3-alkynyl allylic alcohols, the Ag(I)-catalyzed ring closure of allenyl ketones, a ruthenium-promoted alternative involving γ-ethynylallyl alcohols, and 2-fold alkylation of 3-tosylpropanal ethylene ketal with subsequent acidic hydrolysis …”

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Convergent Regiodirected Assembly of 2,3-Disubstituted Furans

Méndez‐Andino

Paquette

2000

Org. Lett.

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A General Method for the Preparation of 2-Substituted and 2,3-Disubstituted Furans. A New Synthesis of Sesquirose Furan

Cited by 25 publications

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Studies on the Structure and Function of Phytochromes as Photoreceptors Based on Synthetic Organic Chemistry

Studies on the Structure and Function of Phytochromes as Photoreceptors Based on Synthetic Organic Chemistry

"Syn-Effect" in the Base-Induced Isomerization of Vinylic Sulfones to Allylic Sulfones and the Related Various Reactions

Convergent Regiodirected Assembly of 2,3-Disubstituted Furans

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