1,3-REARRANGEMENT OF ALLYLIC <i>p</i>-TOLYL SULFONES CATALYZED By [Pd(PPh3)4] AND ITS APPLICATION TO THE SYNTHESIS OF α,β-UNSATURATED KETONES

Inomata, Katsuhiko; Murata, Y.; Kato, Hisatoyo; Tsukahara, Yuhko; Kinoshita, Hideki; Kotake, Hiroshi

doi:10.1246/cl.1985.931

Cited by 18 publications

(3 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…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. Thus obtained allylic sulfones 5 served as versatile synthetic intermediates to provide a wide variety of allylic compounds including 7 and 10, [7][8][9][10][11][12] whose further synthetic elaboration furnished several naturally occurring substances such as squalene, 9 methyl helepuberinate (unpublished work), coenzyme Q 10 , 11 ( )-recifeiolide, 8 ( )-lavandulol, 12 and isolavandulol 12 ( Figure 1). …”

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

: "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: 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

“…This result is in striking contrast to the corresponding sigmatropic process in which (Z)-and (£)isomers give stereocomplementary results. A further difference from the thermal rearrangement is the tendency of this palladium-mediated reaction to give unwanted non-transposed sulphone products (32). This is a particularly acute problem when larger groups are attached to the allylic chain, i.e.…”

Section: Scheme 14mentioning

confidence: 99%

Rearrangements of Sulphones

1993

Sulphones in Organic Synthesis

View full text Add to dashboard Cite

“…We established the relative configuration of 12 ultimately through its conversion to final product 2 . The stereochemical outcome of this stereoselective allylic transposition could be rationalized by a [3,3]-sigmatropic reaction through transition state 13 , in which Pd(II) coordinates to the double bond on the less hindered α-face opposite the acetate group and facilitates the sigmatropic rearrangement on the β-face. , …”

mentioning

confidence: 99%

Efficient Synthesis of (+)-MK7607 and its C-1 Epimer via the Stereoselective Transposition of a Tertiary Allylic Alcohol

et al. 2009

View full text Add to dashboard Cite

show abstract

1,3-REARRANGEMENT OF ALLYLIC p-TOLYL SULFONES CATALYZED By [Pd(PPh3)4] AND ITS APPLICATION TO THE SYNTHESIS OF α,β-UNSATURATED KETONES

Cited by 18 publications

References 2 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

Rearrangements of Sulphones

Efficient Synthesis of (+)-MK7607 and its C-1 Epimer via the Stereoselective Transposition of a Tertiary Allylic Alcohol

Contact Info

Product

Resources

About