Synthesis of 3-Acylfurans Using 3-(Phenylthio)propanal Dimethyl Acetal as a New Synthon. Syntheses of Ipomeanine and Isoegomaketone

Watanabe, Eiji; Imai, Naohiro; Inomata, Katsuhiko; Kinoshita, Hideki; Kotake, Hiroshi

doi:10.1246/bcsj.55.3225

Cited by 10 publications

(5 citation statements)

References 7 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The observed relative degree of "syn-effect" for the g-substituents R of (E)-a-fluorovinylic sulfone 34, 6 H 5 -, seemed to reflect the electronegativity and/or electron donating ability of each substituent along with the steric hindrance supporting the s p* interaction ( Figure 16).…”

Section: 31mentioning

confidence: 99%

“…[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%

See 1 more Smart Citation

"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.

Self Cite

View full text Add to dashboard Cite

: "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...

show abstract

Section: 31mentioning

confidence: 99%

Section: Introductionmentioning

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.

Self Cite

View full text Add to dashboard Cite

show abstract

“…(liquid film) 3 550, 3 470 (OH), 1 580, and 1 510 cm-' (Ph); GH(CDC1,) 6.9-7.8 (14 H, m, 2 PhS and C,H,), 3.9-4.1 and 3.5-3.7 (1 H, m, CHOH, two diastereoisomers), 1.7-3.0 (5 H, m, MeCHCH,, Me2CH and OH), 2.30(3 H, s, MeC&?4), and 1.0-1.3 (9 H, m, 3 Me); m/z Me,CHC(SPh)CHOH], and 165 (60, Me,CHCHSPh). (20).-The water of crystallisation of toluene-p-sulphonic acid monohydrate (80 mg, 0.42 mmol) was removed by azeotropic distillation with benzene and then a solution of the alcohol (19) (157 mg, 0.42 mmol) in benzene (1 ml) was added. After 1 min the mixture was cooled, poured into saturated sodium carbonate solution (20 ml), and extracted with ether (3 x 10 ml).…”

Section: -Methy1-44-bisphenylthio-octan-3-o1(28)-dithioaceta1(27)mentioning

confidence: 99%

“…SOPh SPh only with difficulty and acylation yields are low," though successful acylation of one series of sulphides with aziridine amides has been reported. 20 Changing the oxidation level at both functionalised carbon atoms (Scheme 1) avoids all these problems. Bisphenylthio…”

mentioning

confidence: 99%

A regiospecific route to conjugated enones viaα-phenylthio ketones

Durman¹,

Elliott²,

McElroy³

et al. 1985

J. Chem. Soc., Perkin Trans. 1

View full text Add to dashboard Cite

“…4.1.2. ((3,3)-Dimethoxypropyl)(phenyl)sulfane(2)30 . A solution of 3-(phenylthio)propanal (2.90 g, 17.5 mmol, 1.0 equiv), CH(MeO)3 (3.71 g, 34.9 mmol, 2.0 equiv), p-TsOH$H 2 O (100 mg, 0.526 mmol, 0.03 equiv) and MeOH (35 mL) was heated to 50 C. Then, EtOH (15 mL) was added to the crude, washed with satd aq NaHCO 3 (3Â30 mL), H 2 O (3Â10 mL), brine (2Â15 mL) and dried (Na 2 SO 4 ).…”

mentioning

confidence: 99%

Directed addition of sulfur-stabilised carbanions to 1,2,3-trisubstituted aziridines

Craig

Mathie

et al. 2010

Tetrahedron

View full text Add to dashboard Cite

show abstract

Synthesis of 3-Acylfurans Using 3-(Phenylthio)propanal Dimethyl Acetal as a New Synthon. Syntheses of Ipomeanine and Isoegomaketone

Abstract: It was found that 3-(phenylthio)propanal dimethyl acetal is a very useful starting material for the preparation of 3-acylfuranoterpenes. Syntheses of two naturally-occurring furans, isoegomaketone and ipomeanine were described.

Cited by 10 publications

References 7 publications

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

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

A regiospecific route to conjugated enones viaα-phenylthio ketones

Directed addition of sulfur-stabilised carbanions to 1,2,3-trisubstituted aziridines

Contact Info

Product

Resources

About