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Search for "Takai olefination" in Full Text gives 5 result(s) in Beilstein Journal of Organic Chemistry.
Syntheses of spliceostatins and thailanstatins: a review
- William A. Donaldson
Beilstein J. Org. Chem. 2020, 16, 1991–2006, doi:10.3762/bjoc.16.166
- iodine-catalyzed Mukiyama–Michael addition of the ketene silyl acetal 104 to 103 afforded the trans-1,5-disubstituted tetrahydropyranone 105. After the generation of the C-3-exocyclic olefin and functional group manipulation, the Takai olefination [40] of the aldehyde 106 gave the trans-vinyl iodide 107
Graphical Abstract
Figure 1: Structures of spliceostatins/thailanstatins.
Scheme 1: Synthetic routes to protected (2Z,4S)-4-hydroxy-2-butenoic acid fragments.
Scheme 2: Kitahara synthesis of the (all-cis)-2,3,5,6-tetrasubstituted tetrahydropyran.
Scheme 3: Koide synthesis of (all-cis)-2,3,5,6-tetrasubstituted tetrahydropyran.
Scheme 4: Nicolaou synthesis of the (all-cis)-2,3,5,6-tetrasubstituted tetrahydropyran.
Scheme 5: Jacobsen synthesis of the (all-cis)-2,3,5,6-tetrasubstituted tetrahydropyran.
Scheme 6: Unproductive attempt to generate the (all-cis)-tetrahydropyranone 50.
Scheme 7: Ghosh synthesis of the C-7–C-14 (all-cis)-tetrahydropyran segment.
Scheme 8: Ghosh’s alternative route to the (all-cis)-tetrahydropyranone 50.
Scheme 9: Alternative synthesis of the dihydro-3-pyrone 58.
Scheme 10: Kitahara’s 1st-generation synthesis of the C-1–C-6 fragment of FR901464 (1).
Scheme 11: Kitahara 1st-generation synthesis of the C-1–C-6 fragment of FR901464 (1).
Scheme 12: Nimura/Arisawa synthesis of the C-1-phenyl segment.
Scheme 13: Ghosh synthesis of the C-1–C-6 fragment of FR901464 (1) from (R)-glyceraldehyde acetonide.
Scheme 14: Jacobsen synthesis of the C-1–C-7 segment of FR901464 (1).
Scheme 15: Koide synthesis of the C-1–C-7 segment of FR901464 (1).
Scheme 16: Ghosh synthesis of the C-1–C-5 segment 102 of thailanstatin A (7).
Scheme 17: Nicolaou synthesis of the C-1–C-9 segments of spliceostatin D (9) and thailanstatins A (7) and B (5...
Scheme 18: Ghosh synthesis of the C-1–C-6 segment 115 of spliceostatin E (10).
Scheme 19: Fragment coupling via Wittig and modified Julia olefinations by Kitahara.
Scheme 20: Fragment coupling via cross-metathesis by Koide.
Scheme 21: The Ghosh synthesis of spliceostatin A (4), FR901464 (1), spliceostatin E (10), and thailanstatin m...
Scheme 22: Arisawa synthesis of a C-1-phenyl analog of FR901464 (1).
Scheme 23: Jacobsen fragment coupling by a Pd-catalyzed Negishi coupling.
Scheme 24: Nicolaou syntheses of thailanstatin A and B (7 and 5) and spliceostatin D (9) via a Pd-catalyzed Su...
Scheme 25: The Ghosh synthesis of spliceostatin G (11) via Suzuki–Miyaura coupling.
The chemistry and biology of mycolactones
- Matthias Gehringer and
- Karl-Heinz Altmann
Beilstein J. Org. Chem. 2017, 13, 1596–1660, doi:10.3762/bjoc.13.159
Graphical Abstract
Figure 1: Initial proposal for the core macrolactone structure (left) and the established complete structure ...
Figure 2: Mycolactone congeners and their origins.
Figure 3: Misassigned mycolactone E structure according to Small et al. [50] (11) and the correct structure (6) f...
Figure 4: Schematic illustration of Kishi’s improved mycolactone TLC detection method exploiting derivatizati...
Figure 5: Fluorescent probes derived from natural mycolactone A/B (1a,b) or its synthetic 8-desmethyl analogs...
Figure 6: Tool compounds used by Pluschke and co-workers for elucidating the molecular targets of mycolactone...
Figure 7: Synthetic strategies towards the extended mycolactone core. A) General strategies. B) Kishi’s appro...
Scheme 1: Kishi’s 1st generation approach towards the extended core structure of mycolactones. Reagents and c...
Scheme 2: Kishi’s 2nd generation approach towards the extended core structure of mycolactones. Reagents and c...
Scheme 3: Kishi’s 3rd generation approach towards the extended core structure of mycolactones. Reagents and c...
Scheme 4: Negishi’s synthesis of the extended core structure of mycolactones. Reagents and conditions: a) (i) ...
Scheme 5: Burkart’s (incomplete) 1st generation approach towards the extended core structure of mycolactones....
Scheme 6: Burkart’s (incomplete) 1st, 2nd and 3rd generation approach towards the extended mycolactone core s...
Scheme 7: Altmann’s synthesis of alkyl iodide 91. Reagents and conditions: a) (i) PMB-trichloroacetimidate, T...
Scheme 8: Final steps of Altmann’s synthesis of the extended core structure of mycolactones. Reagents and con...
Scheme 9: Basic principles of the Aggarwal lithiation–borylation homologation process [185,186].
Scheme 10: Aggarwal’s synthesis of the C1–C11 fragment of the mycolactone core. Reagents and conditions: a) Cl...
Scheme 11: Aggarwal’s synthesis of the linear C1–C20 fragment of the mycolactone core. Reagents and conditions...
Figure 8: Synthetic strategies towards the mycolactone A/B lower side chain.
Scheme 12: Gurjar and Cherian’s synthesis of the C1’–C8’ fragment of the mycolactone A/B pentaenoate side chai...
Scheme 13: Gurjar and Cherian’s synthesis of the benzyl-protected mycolactone A/B pentaenoate side chain. Reag...
Scheme 14: Kishi’s synthesis of model compounds for elucidating the stereochemistry of the C7’–C16’ fragment o...
Scheme 15: Kishi’s synthesis of the mycolactone A/B pentaenoate side chain. (a) (i) NaH, (EtO)2P(O)CH2CO2Et, T...
Scheme 16: Feringa and Minnaard's incomplete synthesis of mycolactone A/B pentaenoate side chain. Reagents and...
Scheme 17: Altmann’s approach towards the mycolactone A/B pentaenoate side chain. Reagents and conditions: a) ...
Scheme 18: Negishi’s access to the C1’–C7’ fragment of mycolactone A. Reagents and conditions: a) (i) n-BuLi, ...
Scheme 19: Negishi’s approach to the C1’–C7’ fragment of mycolactone B. Reagents and conditions: a) (i) DIBAL-...
Scheme 20: Negishi’s synthesis of the C8’–C16’ fragment of mycolactone A/B. Reagents and conditions: a) 142, BF...
Scheme 21: Negishi’s assembly of the mycolactone A and B pentaenoate side chains. Reagents and conditions: a) ...
Scheme 22: Blanchard’s approach to the mycolactone A/B pentaenoate side chain. a) (i) Ph3P=C(Me)COOEt, CH2Cl2,...
Scheme 23: Kishi’s approach to the mycolactone C pentaenoate side chain exemplified for the 13’R,15’S-isomer 1...
Scheme 24: Altmann’s (unpublished) synthesis of the mycolactone C pentaenoate side chain. Reagents and conditi...
Scheme 25: Blanchard’s synthesis of the mycolactone C pentaenoate side chain. Reagents and conditions: a) (i) ...
Scheme 26: Kishi’s synthesis of the tetraenoate side chain of mycolactone F exemplified by enantiomer 165. Rea...
Scheme 27: Kishi’s synthesis of the mycolactone E tetraenoate side chain. Reagents and conditions: a) (i) CH2=...
Scheme 28: Wang and Dai’s synthesis of the mycolactone E tetraenoate side chain. Reagents and conditions: a) (...
Scheme 29: Kishi’s synthesis of the dithiane-protected tetraenoate side chain of the minor oxo-metabolite of m...
Scheme 30: Kishi’s synthesis of the mycolactone S1 and S2 pentaenoate side chains. Reagents and conditions: a)...
Scheme 31: Kishi’s 1st generation and Altmann’s total synthesis of mycolactone A/B (1a,b) and Negishi’s select...
Scheme 32: Kishi’s 2nd generation total synthesis of mycolactone A/B (1a,b). Reagents and conditions: a) 2,4,6...
Scheme 33: Blanchard’s synthesis of the 8-desmethylmycolactone core. Reagents and conditions: a) (i) TsCl, TEA...
Scheme 34: Altmann’s (partially unpublished) synthesis of the C20-hydroxylated mycolactone core. Reagents and ...
Scheme 35: Altmann’s and Blanchard’s approaches towards the 11-isopropyl-8-desmethylmycolactone core. Reagents...
Scheme 36: Blanchard’s synthesis of the saturated variant of the C11-isopropyl-8-desmethylmycolactone core. Re...
Scheme 37: Structure elucidation of photo-mycolactones generated from tetraenoate 224.
Scheme 38: Kishi’s synthesis of the linear precursor of the photo-mycolactone B1 lower side chain. Reagents an...
Scheme 39: Kishi’s synthesis of the photo-mycolactone B1 lower side chain. Reagents and conditions: a) LiTMP, ...
Scheme 40: Kishi’s synthesis of a stabilized lower mycolactone side chain. Reagents and conditions: a) (i) TBD...
Scheme 41: Blanchard’s variation of the C12’,C13’,C15’ stereocluster. Reagents and conditions: a) (i) DIBAL-H,...
Scheme 42: Blanchard’s synthesis of aromatic mycolactone polyenoate side chain analogs. Reagents and condition...
Scheme 43: Small’s partial synthesis of a BODIPY-labeled mycolactone derivative and Demangel’s partial synthes...
Scheme 44: Blanchard’s synthesis of the BODIPY-labeled 8-desmethylmycolactones. Reagents and conditions: a) (i...
Scheme 45: Altmann’s synthesis of biotinylated mycolactones. Reagents and conditions: a) (i) CDI, THF, rt, 2 d...
Figure 9: Kishi’s elongated n-butyl carbamoyl mycolactone A/B analog.
(Z)-Selective Takai olefination of salicylaldehydes
- Stephen M. Geddis,
- Caroline E. Hagerman,
- Warren R. J. D. Galloway,
- Hannah F. Sore,
- Jonathan M. Goodman and
- David R. Spring
Beilstein J. Org. Chem. 2017, 13, 323–328, doi:10.3762/bjoc.13.35
- Stephen M. Geddis Caroline E. Hagerman Warren R. J. D. Galloway Hannah F. Sore Jonathan M. Goodman David R. Spring Department of Chemistry, University of Cambridge, Lensfield Rd, Cambridge, CB2 1EW, UK 10.3762/bjoc.13.35 Abstract The Takai olefination (or Takai reaction) is a method for the
- conversion of aldehydes to vinyl iodides, and has seen widespread implementation in organic synthesis. The reaction is usually noted for its high (E)-selectivity; however, herein we report the highly (Z)-selective Takai olefination of salicylaldehyde derivatives. Systematic screening of related substrates
- led to the identification of key factors responsible for this surprising inversion of selectivity, and enabled the development of a modified mechanistic model to rationalise these observations. Keywords: alkenyl iodides; salicylaldehydes; stereoselectivity; Takai olefination; transition state
Graphical Abstract
Scheme 1: A) General overview of the Takai olefination for the formation of alkenyl halides 2 from aldehydes 1...
Scheme 2: Proposed model for the chromium(II)-mediated homologation of aldehydes to form (E)-alkenes. Hodsgon...
Scheme 3: An unusually high level of (Z)-stereoselectivity was observed in the Takai olefination of 6. (E):(Z...
Scheme 4: Takai olefination of meta-hydroxybenzaldehyde.
Scheme 5: Yield for both products and residual starting material following a scaled up Takai olefination of s...
Figure 1: Positive correlation between the amount (Z)-product and σm for the series of meta-halogenated salic...
Scheme 6: Proposed mechanism for (Z)-selective Takai olefination, whereby coordination of the ortho-OH to the...
Selective bromochlorination of a homoallylic alcohol for the total synthesis of (−)-anverene
- Frederick J. Seidl and
- Noah Z. Burns
Beilstein J. Org. Chem. 2016, 12, 1361–1365, doi:10.3762/bjoc.12.129
- two enantiomers (or pseudoenantiomers) of a substrate allylic alcohol. Tetrahalide 11 was then oxidized to the corresponding aldehyde. Installation of the vinyl bromide was found to be difficult using traditional methods. Takai olefination [14] with CHBr3 and CrBr2 resulted in significant de
Graphical Abstract
Scheme 1: Selective bromochlorination and possible disconnections for anverene (1).
Scheme 2: Selective total synthesis of (−)-anverene. Reagents and conditions: a) NBS (1.2 equiv), ClTi(OiPr)3...
A reductive coupling strategy towards ripostatin A
- Kristin D. Schleicher and
- Timothy F. Jamison
Beilstein J. Org. Chem. 2013, 9, 1533–1550, doi:10.3762/bjoc.9.175
- Takai olefination [36] was used to generate the E-vinyl iodide. The vinyl iodide was sufficiently stable for purification by silica gel chromatography but, following purification, was immediately carried forward to a Sonogashira reaction with propyne [37]. The enyne could be obtained in 15:1 E/Z
- selectivity, in 10 steps and 35% overall yield. It was found that the use of freshly distilled THF in the Takai olefination and careful temperature control in the subsequent cross coupling were critical to the preservation of high E/Z selectivity over the course of these transformations. Once isolated
Graphical Abstract
Figure 1: Structures of the ripostatins.
Figure 2: Retrosynthesis of ripostatin A.
Scheme 1: Nickel-catalyzed reductive coupling of alkynes and epoxides.
Figure 3: Proposed retrosynthesis of ripostatin A featuring enyne–epoxide reductive coupling and rearrangemen...
Scheme 2: Potential transition states and stereochemical outcomes for a concerted 1,5-hydrogen rearrangement.
Scheme 3: Rearrangements of vinylcyclopropanes to acylic 1,4-dienes.
Scheme 4: Synthesis of cyclopropyl enyne.
Scheme 5: Synthesis of model epoxide for investigation of the nickel-catalyzed coupling reaction.
Scheme 6: Nickel-catalyzed enyne–epoxide reductive coupling reaction.
Scheme 7: Proposed mechanism for the nickel-catalyzed coupling reaction of alkynes or enynes with epoxides.
Scheme 8: Regioselectivity changes in reductive couplings of alkynes and 3-oxygenated epoxides.
Scheme 9: Enyne reductive coupling with 1,2-epoxyoctane.
Figure 4: Initial retrosynthesis of the epoxide fragment by using dithiane coupling.
Scheme 10: Synthesis of dithiane by Claisen rearrangement.
Scheme 11: Deuterium labeling reveals that the allylic/benzylic site is most acidic.
Scheme 12: Oxy-Michael addition to δ-hydroxy-α,β-enones.
Figure 5: Revised retrosynthesis of epoxide 5.
Scheme 13: Synthesis of functionalized ketone by oxy-Michael addition.
Figure 6: Retrosynthesis by using iodocylization to introduce the epoxide.
Scheme 14: Synthesis of ketone 57 using thiazolidinethione chiral auxiliary.
Figure 7: Retrosynthesis involving decarboxylation of a β-ketoester.
Scheme 15: Synthesis of β-ketoester 61.
Scheme 16: Decarboxylation of 61 under Krapcho conditions.
Scheme 17: Improved synthesis of 63 and attempted iodocyclization.
Figure 8: Retrosynthesis utilizing Rychnovsky’s cyanohydrin acetonide methodology.
Scheme 18: Synthesis of cyanohydrin acetonide and attempted alkylation with epoxide.
Scheme 19: Allylation of acetonide and conversion to aldehyde.
Scheme 20: Synthesis of the epoxide precursor by an aldol−decarboxylation sequence.
