Synthesis and Anionically Induced Domino Reactions of Chiral α-Bromo α,β-Unsaturated Esters

Braun, Norbert A.; Bürkle, Ulrike; Feth, Martin P.; Klein, I.; Spitzner, D.

doi:10.1002/(sici)1099-0690(199808)1998:8<1569::aid-ejoc1569>3.0.co;2-w

Cited by 15 publications

(3 citation statements)

References 26 publications

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“…The corresponding (Z)-1 can be analogously prepared from aldehyde 9 by a (Z)-selective Wittig type olefination. 12 Synthetic alcohol (Z)-1 was identical in all respects ( 1 H, 13 C-NMR, GC-MS, RI) to the natural product (Z)-1 described by Braun et al from Western Australian sandalwood oil. 5 Enantiomerically pure β-curcumenol (1) may be prepared starting from enantiopure aldehyde 9 following the protocol of Ogasawara et al 13 With the synthetic sample of (E)-1 in hand, we reinvestigated various commercially available sandalwood oils and were able to detect this so far unknown isomer for the first time as a new minor constituent in nature.…”

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confidence: 73%

Synthesis and natural occurrence of (Z/E)-β-and γ-curcumen-12-ol

Braun¹,

Spitzner²

2006

Arkivoc

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Section: Resultsmentioning

confidence: 73%

Synthesis and natural occurrence of (Z/E)-β-and γ-curcumen-12-ol

Braun¹,

Spitzner²

2006

Arkivoc

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“…To further reduce the electron density in the α,β-double bond as well as increase the steric bulk, a vinylic bromide was introduced at the α-carbon. Compound 9 , ( 2Z ,4 E )-2-bromoethyl sorbate, was prepared according to a literature procedure by Spitzner et al and was used as a 9:1 mixture of 2 Z /2 E isomers. This substrate could give synthetically interesting and useful products because both the vinyl bromide and the ester group can be further functionalized.…”

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Chemoselective Construction of Substituted Conjugated Dienes Using an Olefin Cross-Metathesis Protocol

2004

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General Experimental Section. NMR spectra were recorded on an Oxford 300 MHz NMR spectrometer running Varian VNMR software. Chemical shifts are reported in parts per million (ppm) downfield from tetramethylsilane (TMS) with reference to internal solvent. Multiplicities are abbreviated as follows: singlet (s), doublet (d), triplet (t), quartet (q), quintet (quint), multiplet (m), and broad (br). Spectroscopic data is provided for the major olefin isomer. For all vinylboronates reported the 13 C peak of the α-carbon is not observed due to the large quadrupolar effect of the attached boron nucleus. E/Z ratios given for the products indicate the ratios of the C=C bond formed in cross-metathesis and were determined from coupling constants of vinylic protons in the 1 H NMR spectrum.Analytical thin-layer chromatography (TLC) was performed using silica gel 60 F254 precoated plates (0.25 mm thickness) with a fluorescent indicator. Visualization was performed with standard potassium permanganate stains or UV light. Flash column chromatography was performed using silica gel 60 (230-400 mesh). All glassware was either oven dried or flame dried, and reactions were done under an atmosphere of argon.All commercial chemicals were used as obtained except 1,4-diacetoxy-cis-2-butene,

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“…α-Haloacrylates are important functional intermediates and broadly used in the synthesis of polymers, biologically active molecules, as well as natural products, especially when they were explored as good substrates in transition metal-catalyzed coupling reactions for synthesis of trisubstituted olefins , Wittig reaction starting from α-halophosphonium ylide and the corresponding aldehyde was still one of the most mild and straightforward synthetic protocols many of which suffered from the use of hazardous or expensive halogenation reagents, harsh reaction conditions, and unavoidable side reactions …”

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confidence: 99%