133350-18-2Relevant academic research and scientific papers
Ruthenium-catalyzed cyclic carbonylation of allenyl alcohols. Selective synthesis of γ- and δ-lactones
Yoneda, Eiji,Kaneko, Takayuki,Zhang, Shi-Wei,Onitsuka, Kiyotaka,Takahashi, Shigetoshi
, p. 441 - 443 (2000)
(Formula presented) Ruthenium complex-catalyzed carbonylation of allenyl alcohols quantitatively gave cyclic carbonyl compounds, γ- and δ-lactones, in which the hydroxy group of allenyl alcohols participated in the cyclization. A wide variety of allenyl alcohols, such as mono-, di-, and trisubstituted alcohols, can be used in this reaction to produce 3- and 4-substituted γ-lactones. Similarly, the cyclic carbonylation of 3,4-pentadien-1-ol 10a and 2-methyl-4,5-hexadien-2-ol 11a gave δ-lactones, 5,6-dihydro-3-methyl-2H-pyran-2-one 10b, and 5,6-dihydro-6,6-dimethyl-3-methyl-2H-pyran-2-one 11b, respectively, in a quantitative yield.
3-Alkoxy-2,5-dihydrofurans by gold-catalyzed allenyl cyclizations and their transformation into 1,4-dicarbonyl compounds, cyclopentenones, and butenolides
Brasholz, Malte,Dugovi, Branislav,Reissig, Hans-Ulrich
supporting information; experimental part, p. 3855 - 3864 (2010/12/25)
The addition of lithiated alkoxyallenes to carbonyl compounds furnishes allenyl alcohols, which undergo a highly efficient and chemoselective 5-endo-trig cyclization to 3-alkoxy-2,5-dihydrofurans catalyzed by gold(I) chloride. The dihydrofurans produced can be either oxidized to -alkoxy butenolides by a manganese(III) acetate catalyzed radical oxidation with tert-butyl hydroperoxide, or transformed into ,-unsaturated -keto aldehydes by an oxidative ring cleavage using DDQ in the presence of water. Treatment of the -keto aldehydes with sodium methoxide in methanol promotes a diastereoselective intramolecular aldol addition furnishing alkoxy-substituted cyclopentenone derivatives in good yield. Georg Thieme Verlag Stuttgart · New York.
Refined protocols for the preparation of 3-alkoxy-2,5-dihydrofurans, allylic oxidation to β-alkoxybutenolides and short synthesis of (±)-annularin H
Brasholz, Malte,Reissig, Hans-Ulrich
, p. 1294 - 1298 (2008/02/08)
The 5-endo cyclization of α-allenyl alcohols derived from carbonyl compounds and lithiated alkoxyallenes was reinvestigated by comparing the known reagents KOt-Bu, AgNO3 or AgBF4 with the reagent system AuCl/pyridine. A variety of 3-
Preparation of α,β-Unsaturated γ-Keto Aldehydes and New Tetronic Acid and Pyridazine Derivatives by Oxidative Transformations of Alkoxyallene-Based Dihydrofurans
Floegel, Oliver,Reissig, Hans-Ulrich
, p. 2797 - 2804 (2007/10/03)
Oxidation of 3-alkoxy-substituted dihydrofuran derivatives 6 and 11 with DDQ unexpectedly provided α,β-unsaturated γ-keto aldehydes 10 and 12. A mechanism for this new oxidative ring-cleavage is presented. Since α,β-unsaturated γ-keto aldehydes are versatile intermediates, other 3-methoxy-substituted dihydrofuran derivatives 24, 26, and 28 were prepared from lithiated methoxyallene and the corresponding aldehydes. Oxidation of dihydrofuran derivatives with DDQ and subsequent treatment with sodium chlorite furnished hydroxy-substituted tetronic acid derivatives, such as 30 and 31. Condensation of 30 with hydrazine provided the unsaturated pyridazinone derivative 32. A second route to pyridazine derivatives involves DDQ-mediated oxidation of dihydrofurans and reaction of the products with hydrazine hydrate. This leads to 4-methoxypyridazines 33, 34, 35, and 36 in good overall yields. The oxidative transformations of dihydrofuran derivatives reported here demonstrate new examples of reactivity umpolung; the lithiated alkoxyallenes are equivalents of the unusual synthons B and C, which represent anions of malondialdehyde or malonaldehydic acid.
Stereoselective Synthesis of (2S,3S)-Norstatine Derivatives by Addition of Lithiated Methoxyallene to Amino Aldehydes and Subsequent Ozonolysis
Hormuth, Stephan,Reissig, Hans-Ulrich,Dorsch, Dieter
, p. 121 - 128 (2007/10/02)
Addition of lithiated methoxyallene 2 to optically active N-benzyl-Boc-protected amino aldehydes 12-14 and to aldehyde 16 provides products 17-20 with good to excellent diastereoselectivity.These adducts are subsequently cleaved by ozonolysis to give α-hydroxy-β-amino acid derivatives 21-25 in good overall yield.By conversion into an oxazolidone derivative, the configuration of the major diastereomer was determined to be anti (2S,3S).Thus, the additions of 2 follow the course proposed by the Felkin-Anh model and are not ruled by chelation effects.The diastereoselective synthesis of 22 constitutes one of the simplest routes to a protected norstatine derivative. - Key Words: Methoxyallene / Allenes / Aldehydes, α-amino / Lithium compounds / Ozonolysis / Norstatine derivatives
Stereoselective synthesis of 3(2H)-dihydrofuranones by addition of lithiated methoxyallene to chiral aldehydes
Hormuth,Reissig
, p. 67 - 73 (2007/10/02)
Lithiated methoxyallene 2 adds to chiral aldehydes such as 2- phenylpropanal and N,N-dibenzylated α-amino aldehydes 4-8 to give products 9-14 in good yields and with excellent anti-selectivity. The stereochemical outcome of these reactions can be explained by the Felkin-Anh model in a straightforward manner. The crude reaction products can either be transformed to enones by hydrolysis with acid or be converted into 2,5-dihydro-3- methoxyfuran derivatives 19-24 by treatment with potassium tert-butoxide in DMSO. The latter can be hydrolyzed to give 3(2H)-dihydrofuranones 25-29. The diastereoselectivity of the initial addition step is transferred to the dihydrofuran derivative without a major change in the isomer ratio. Compounds derived from α-amino aldehydes 5, 6, and 8 are assumed to be enantiomerically pure. Sodium borohydride reductions of and Grignard additions to 3(2H)-dihydrofuranones 27a and 28a demonstrate that these chiral ketones react in a highly diastereoselective manner. In summary, this paper shows that lithiated methoxyallene 2 can serve as a very useful equivalent for α,β-unsaturated acyl anions and 1,3-dipolar synthons in asymmetric synthesis.
Synthesis of 6H-1,2-Oxazines by Hetero Diels-Alder Reactions of Nitroso Alkenes towards Methoxyallenes
Zimmer, Reinhold,Reissig, Hans-Ulrich
, p. 553 - 562 (2007/10/02)
Regioselective hetero Diels-Alder reactions of in-situ generated nitroso alkenes 2-4 with methoxyallene derivatives 1 provide 4H-1,2-oxazines 5-7 with an exo methylene group at C-5.These primary cycloadducts are smoothly transformed into conjugated 6H-1,2
