1892-05-3Relevant academic research and scientific papers
Synthetic Access to Noncanonical Strigolactones: Syntheses of Carlactonic Acid and Methyl Carlactonoate
Dieckmann, Michael C.,Dakas, Pierre-Yves,De Mesmaeker, Alain
, p. 125 - 135 (2017/12/15)
Strigolactones are plant hormones regulating essential stages of a plant's development. Their low natural abundance combined with a low chemical stability significantly hampered the detailed investigation of their biological activity. Noncanonical strigolactones lack the fused tricyclic ABC-ring system commonly present in canonical-type strigolactones but feature an open-chain unit linking structurally diverse A-ring moieties to the butenolide D-ring. We herein present an efficient synthetic access to enantiomerically pure noncanonical strigolactones by a Stille cross-coupling approach to forge the central diene moiety and demonstrate this strategy by syntheses of natural products methyl carlactonoate and carlactonic acid. Furthermore, a synthetic access to deuterium-labeled analogues of these natural products has been developed.
Cu(I)-catalyzed oxidative cyclization of alkynyl oxiranes and oxetanes
Gronnier, Colombe,Kramer, Soren,Odabachian, Yann,Gagosz, Fabien
supporting information; experimental part, p. 828 - 831 (2012/03/07)
In the presence of a Cu(I) catalyst and a pyridine oxide, alkynyl oxiranes and oxetanes can be converted into functionalized five- or six-membered α,β-unsaturated lactones or dihydrofuranaldehydes. This new oxidative cyclization is proposed to proceed via an unusual allenyloxypyridinium intermediate.
Synthesis of the 2-alkenyl-4-alkylidenebut-2-eno-4-lactone (=α-alkenyl-γ-alkylidenebutenolide) core structure of the carotenoid pyrrhoxanthin via the regioselective dihydroxylation of hepta-2,4-diene-5-ynoic acid esters
Schmidt-Leithoff, Joachim,Brueckner, Reinhard
, p. 1943 - 1959 (2007/10/03)
A new strategy for the stereoselective synthesis of 4-alkylidenebut-2-eno- 4-lactones (= γ-alkylidenebutenolides) with (Z)-configuration of the exocyclic C=C bond at C(4) was developed. It is exemplified by the synthesis of 4-alkylidenebutenolactone 31 (Scheme 4), which constitutes a substructure of the carotenoids pyrrhoxanthin (1) and peridinin. The formation of the precursor 4-(1-hydroxyalkyl)butenolactone 29 was accomplished either by cyclocarbonylation of the prop-2-yn-1-ol moiety of 27 (→ 29) or by hydrostannylation of the isopropylidene-protected alkynoic acid ester 26 (->28) followed by transacetalization/transesterification (→ 30). The 4- alkylidenebutenolactone was formed by the ami-selective Mitsunobu dehydration 29 → 31.
A comprehensive survey of Stille-type C(sp2)-C(sp2) single bond forming processes in the synthesis of retinoic acid and analogs
Dominguez, Beatriz,Iglesias, Beatriz,De Lera, Angel R.
, p. 15071 - 15098 (2007/10/03)
The synthesis of the retinoid skeleton has been exhaustively explored using the Stille coupling for the formation of the side- chain single bonds. On employing the experimental catalytic conditions developed by Farina [Pd2(dba)3, AsPh3, NMP] we have modified the electronic and steric requirement of the coupling partners, alkenyl stannanes and electrophiles (alkenyl iodides and triflates). The comprehensive survey afforded appropriately matched components for every bond formation considered. Moreover, from the comparison of the reactivities of different coupling partners with different degrees of steric hindrance, the sensitivity of the Stille coupling to steric effects was confirmed. Besides providing a variety of building blocks for retinoid synthesis, the study highlights some trends that might be useful for the application of the Stille reaction to the synthesis of unsubstituted conjugated polyenes.
HIGHLY STEREOSELECTIVE AND GENERAL SYNTHESIS OF (Z)-3-METHYL-2-ALKEN-1-OLS VIA PALLADIUM-CATALYZED CROSS COUPLING OF (Z)-3-IODO-2-BUTEN-1-OL WITH ORGANOZINCS AND OTHER ORGANOMETALS
Negishi, Ei-ichi,Ay, Mehmet,Gulevich, Yuri V.,Noda, Yumiki
, p. 1437 - 1440 (2007/10/02)
The reaction of Zn-protected (Z)-3-iodo-2-buten-1-ol with organozincs in the presence of 1-5 mol percent of a Pd complex, e.g., Pd(PPh3)4 or Cl2Pd(PPh3)2 and n-BuLi (2 equiv), in DMF provides a highly stereoselective (>/= 96 percent), general, and high-yi
The Diels-Alder Route to Drimane related Sesquiterpenes; Synthesis of Cinnamolide, Polygodial, Isodrimeninol, Drimenin and Warburganal
Hollinshead, David M.,Howell, S. Christopher,Ley, Steven V.,Mahon, Michael,Ratcliffe, Norman M.,Worthington, Paul A.
, p. 1579 - 1589 (2007/10/02)
The stereospecific preparation of various 1-vinyl-2,6,6-trimethylcyclohex-1-enes (6) as potential diene precursors in the Diels-Alder reaction with dimethyl acetylenedicarboxylate have been investigated.The reaction of the parent diene (6a) with dimethyl acetylenedicarboxylate affords an adduct (18) in 94percent yield.This species was reductively isomerised using 10percent Pd/C/H2 and a mineral acid to give a trans-fused decalin diester (19).Reduction of (19) with lithium aluminium hydride afforded 1,4,4a,5,6,8,8a-octahydro-5,8,8a-trimethyl-1β,4aα,8aβ-naphthalene-1,2-dimethanol (24) a key starting material for the highly efficient syntheses of five drimane sesquiterpene natural products, cinnamolide (1), polygodial (2), isodrimeninol (3), drimenin (4), and warbuganal (5).Microbial oxidation reactions using C. elegans or A. niger of (2), (24), and (1) gave good yields of the corresponding 3β-hydroxy derivatives, (30), (31), and (32).Several other unusually substituted drimane derivatives are reported.
