Stereoselective synthesis of conjugated trans-enynes readily convertible into conjugated cis,trans-dienes and its application to the synthesis of the pheromone bombykol

Negishi, Ei‐ichi; Lew, George; Yoshida, Takao

doi:10.1039/c39730000874

Cited by 75 publications

(21 citation statements)

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“…Evolutions within the authors' group actually began with the development of some selective C–C bond formation reactions of alkenylboranes leading to most probably the earliest highly selective (≥98%) syntheses of unsymmetrically substituted conjugated ( E, E )- and ( E, Z )-dienes16, following the pioneering studies of alkyne hydroboration by Brown17 and subsequent C–C bond formation by Zweifel18 (Scheme 2). …”

Section: Introductionmentioning

confidence: 99%

Alkyne Elementometalation−Pd-Catalyzed Cross-Coupling. Toward Synthesis of All Conceivable Types of Acyclic Alkenes in High Yields, Efficiently, Selectively, Economically, and Safely: “Green” Way

et al. 2010

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Palladium-catalyzed cross-coupling reactions, especially those involving Zn, Al, Zr (Negishi coupling) and B (Suzuki coupling), collectively have brought about "revolutionary" changes in organic synthesis. Thus, two regio-and stereodefined carbon groups generated as R 1 M (M = Zn, Al, B, Cu, Zr, etc.) and R 2 X (X = I, Br, OTs, etc.) may now be cross-coupled to give R 1 -R 2 with essentially full retention of all structural features. For alkene syntheses, alkyne elementometalation reactions including hydrometalation (B, Al, Zr, etc.), carbometalation (Cu, Al-Zr, etc.), and haloboration (BX 3 where X is Cl, Br, and I) have proven to be critically important. Some representative examples of highly efficient and selective (≥98%) syntheses of di-, tri-and oligoenes containing regio-and stereodefined di-and trisubstituted alkenes of all conceivable types will be discussed with emphasis on those of natural products. Some interesting but undesirable cases involving loss of the initial structural identities of the alkenyl groups are attributable to the formation of allylpalladium species, which must be either tamed or avoided. Some such examples involving the synthesis of 1,3-, 1,4-, and 1,5-dienes will also be discussed.

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Section: Introductionmentioning

confidence: 99%

Alkyne Elementometalation−Pd-Catalyzed Cross-Coupling. Toward Synthesis of All Conceivable Types of Acyclic Alkenes in High Yields, Efficiently, Selectively, Economically, and Safely: “Green” Way

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“…Following some promising leads of Brown (21) and Zweifel and co-workers (22-25), we reported in 1973 a couple of highly selective routes to 1,4-disubstituted (E,E)-and (E,Z)-1,3-dienes (1,3,26), which appear to represent the earliest syntheses of unsymmetrically substituted conjugated dienes in very high (≥97%) selectivity via organometallic alkenylation.…”

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confidence: 99%

“…Of interest in this study are those containing conjugated dienes and oligoenes (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11) (Fig. 1).…”

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confidence: 99%

Highly selective synthesis of conjugated dienoic and trienoic esters via alkyne elementometalation–Pd-catalyzed cross-coupling

Wang

Mohan

Negishi

2011

Proc. Natl. Acad. Sci. U.S.A.

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All four stereoisomers (7-10) of ethyl undeca-2,4-dienoate were prepared in ≥98% isomeric purity by Pd-catalyzed alkenylation (Negishi coupling) using ethyl (E)-and (Z)-β-bromoacrylates. Although the stereoisomeric purity of the 2Z,4E-isomer (8) prepared by Suzuki coupling using conventional alkoxide and carbonate bases was ≤95%, as reported earlier, the use of CsF or n Bu4NF as a promoter base has now been found to give all of 7-10 in ≥98% selectivity. Other widely known methods reveal considerable limitations. Heck alkenylation was satisfactory for the syntheses of the 2E,4E and 2E,4Z isomers of ≥98% purity, but the purity of the 2Z,4E isomer was ≤95%. Mutually complementary HornerWadsworth-Emmons and Still-Gennari (SG) olefinations are also of considerably limited scopes. Neither 2E,4Z nor 2Z,4Z isomer is readily prepared in ≥90% selectivity. In addition to (2Z,4E)-dienoic esters, some (2Z,4E,6E)-and (2Z,4E,6Z)-trienoic esters have been prepared in ≥98% selectivity by a newly devised Pd-catalyzed alkenylation-SG olefination tandem process. As models for conjugated higher oligoenoic esters, all eight stereoisomers for ethyl trideca-2,4,6-trienoate (23-30) have been prepared in ≥98% overall selectivity.highly selective synthesis | Pd-catalyzed Negishi coupling A lkenes represent a large number of natural products of bioactive and medicinally important compounds. Of interest in this study are those containing conjugated dienes and oligoenes (1-11) (Fig. 1). Among numerous known methods for the syntheses of alkenes including conjugated dienes and oligoenes (12, 13), carbonyl olefination reactions, notably Wittig olefination (14) and its variants, such as Horner-Wadsworth-Emmons (HWE hereafter) (15, 16), and Still-Gennari (SG hereafter) (17) as well as Ando (18) modifications have been widely used along with related Si-promoted (Peterson) (19) and S-promoted (Julia and Paris) (20) olefination reactions. As useful as these reactions are, they often lack very high (≥98%) stereoselectivity.In search for highly (≥98%) stereoselective alkene synthesis methodology, our attention was initially drawn to alkyne hydroboration, which generally proceeds in >99% syn-selectivity. Following some promising leads of Brown (21) and Zweifel and co-workers (22-25), we reported in 1973 a couple of highly selective routes to 1,4-disubstituted (E,E)-and (E,Z)-1,3-dienes (1, 3, 26), which appear to represent the earliest syntheses of unsymmetrically substituted conjugated dienes in very high (≥97%) selectivity via organometallic alkenylation.Despite highly selective and satisfactory results described above, our continued search for a more generally applicable and straightforward route to conjugated di-and oligoenes led to the discovery in 1976 of the Pd-catalyzed alkenyl-alkenyl coupling with alkenylalanes (27) and subsequently with alkenyl derivatives containing Zr (28) and Zn (29), collectively known as Negishi coupling (30,31). Along with the subsequently developed alkenylboron version (Suzuki coupling) (32-34), the Pd-catalyzed alken...

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“…6 Although trisubstituted alkene intermediates, such as 2 and 3, were generated, protonolysis of the C-B bonds led only to the formation of disubstituted alkenes and their derivatives. This method was soon supplanted by the Pd-catalyzed cross-coupling with Al, 7,8 Zn,8,9 and Zr,8,10 discovered and developed by us during the 1976-1978 period and by subsequent developments involving organometals containing B, 11 Cu, 12 Sn, 13 and others.…”

Section: Resultsmentioning

confidence: 99%

Highly Stereo- and Regioselective Synthesis of (Z)-Trisubstituted Alkenes via 1-Bromo-1-alkyne Hydroboration−Migratory Insertion−Zn-Promoted Iodinolysis and Pd-Catalyzed Organozinc Cross-Coupling

Huang

Negishi

2007

J. Am. Chem. Soc.

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Hydroboration of 1-bromo-1-alkynes with dibromoborane followed by addition of 3 or 4 equiv of Me 2 Zn provides an efficient and selective route to (Z)-2-alkenyldimethylboranes (3) or (Z)-2-alkenylmethylzincs (4), respectively, which have been successfully applied to one-pot Suzuki (B-I) or Negishi (Zn-I) coupling in some less demanding cases. However, in more demanding crosscoupling reactions, only the use of either (Z)-2-alkenyliodides (5) or the alkenylzincs prepared from lithiation and then zincation of 5 proves to be highly satisfactory (Zn-II or Zn-III protocol). On the contrary, the corresponding organoboron coupling under B-II or B-III protocol appears to be less satisfactory. Preliminary studies indicate that certain substituents proximal to trisubstituted alkenes seriously affect the course of the desired alkenylboron cross-coupling.

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Stereoselective synthesis of conjugated trans-enynes readily convertible into conjugated cis,trans-dienes and its application to the synthesis of the pheromone bombykol

Cited by 75 publications

References 0 publications

Alkyne Elementometalation−Pd-Catalyzed Cross-Coupling. Toward Synthesis of All Conceivable Types of Acyclic Alkenes in High Yields, Efficiently, Selectively, Economically, and Safely: “Green” Way

Alkyne Elementometalation−Pd-Catalyzed Cross-Coupling. Toward Synthesis of All Conceivable Types of Acyclic Alkenes in High Yields, Efficiently, Selectively, Economically, and Safely: “Green” Way

Highly selective synthesis of conjugated dienoic and trienoic esters via alkyne elementometalation–Pd-catalyzed cross-coupling

Highly Stereo- and Regioselective Synthesis of (Z)-Trisubstituted Alkenes via 1-Bromo-1-alkyne Hydroboration−Migratory Insertion−Zn-Promoted Iodinolysis and Pd-Catalyzed Organozinc Cross-Coupling

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