Synthesis of quassinoids. 5. Conversion of D-ring seco derivatives of cholic acid to .delta.-lactones

Dias, Jerry Ray; Ramachandra, R.

doi:10.1021/jo00442a030

Cited by 10 publications

(4 citation statements)

References 10 publications

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“…In the proton-decoupled 13C NMR spectrum, there are two kinds of carbon that couple with 15N, one at 133.2 (Vi3Cisn = 6.9 Hz, C3) and the other at 145.5 (Vi3CisN = 11.7 Hz, C2/). Furthermore, the ring transformation was definitely confirmed by an examination of the non-proton- 1) LDA, (2) p-ClC6H4CN, (3) H20; (c) hv (Pyrex filter) or .…”

Section: Resultsmentioning

confidence: 80%

“…The parent adduct 3a was too unstable to be purified by preparative TLC or recrystallization, but the vinyl proton at 5.93 (s) and the amino proton at 4.4 (br s) were observed in the NMR spectrum (CDC13) of the crude sample. On the other hand, satisfactory spectral data were obtained for each 3 with a p-chlorophenyl group as Ar1 due to their considerable stability as compared with 3a (Scheme III).…”

Section: Resultsmentioning

confidence: 99%

“…The total N-SIV-N length of sulfuranes 18 can be assumed to remain constant (3.80 Á) during the movement of the sulfur atom, because the total S-SIV-S length of thiathiophthenes stays at 4.68 ± 0.06 Á where the length of each S-SIV differs at most by 0.30 Á. 3 The central sulfur atom is invoked to move back and forth as a pendulum on the hypervalent bond at least by 0.46 Á starting from sulfurane I formed from 3-(1.67 + 2.13) to symmetric sulfurane II (1.90 + 1.90) and moves further to the other sulfurane I (2.13 + 1.67) in order to go to 3-/3 according to sigmatropic shift of the hydrogens. The rate of the movement of the sulfur atom in neutral nonpolar solvents is estimated to be around 1 X 10"5 s'1, AH* = 12 kcal mol"1, AS* = -40 eu at 25 °C.…”

Section: Discussionmentioning

confidence: 99%

“…(b) Akiba, K.; Noda, A.; Ohkata, K.; Akiyama, T.; Yamamoto, Y. Heterocycles 1981, 15, 1155. (9) Iwasaki, F.; Akiba, K. Acta Crystallogr., Sect. B 1981, B37, 185. 0002-7863/85/1507-2721$01.50/0 © 1985 American Chemical Society In order to avoid this complication and to present an ideal system for reversible ring transformation via a hypervalent sulfurane, we now report the preparation and structure determination of 5-(2amino-2-arylvinyl)-3-arylisothiazoles (3) and also the synthesis of pure a form of 3 and the kinetics of equilibration between a form and ß form (Scheme I).…”

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confidence: 99%

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Ring transformation equilibrium (bond switch) in 5-(2-aminovinyl)isothiazole system via hypervalent sulfurane. Synthesis, structure determination, and kinetic study

Akiba¹,

Kashiwagi²,

Ohyama³

et al. 1985

J. Am. Chem. Soc.

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Reaction of 3-aryl-5-methylisothiazoles (4) with aromatic nitriles afforded the adducts 3, 5-(2-amino-2-arylvinyl)-3-arylisothiazole derivatives, in the presence of LDA. By employing p-chlorobenzonitrile-15lV, the presence of ring transformation from one isothiazole (a form) to another isothiazole {ß form) was verified. By spectral analyses of 3 compared with 5-[2-(silylamino)-2-arylvinyl]-3-arylisothiazole (13-Z), 3 was concluded to have trans geometry (3-Z) with respect to two aromatic rings to arrange N-8••• linearly. The pure a isomers of 15N-labeled 3d (3d*-a-Z: Ar1 = Ar2 = p-ClC6H4), 3b (Ar1 = p-C1C6H4, Ar2 = p-MeC6H4), and 3e (Ar1 = p-ClC6H4, Ar2 = 3,5-Cl2C6H3) were synthesized by desilylation of 13b, 13d*, and 13e-Z and the equilibrium between a form and ß form has been shown to take place in neutral solutions. A

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Section: Resultsmentioning

confidence: 80%

Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

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Ring transformation equilibrium (bond switch) in 5-(2-aminovinyl)isothiazole system via hypervalent sulfurane. Synthesis, structure determination, and kinetic study

Akiba¹,

Kashiwagi²,

Ohyama³

et al. 1985

J. Am. Chem. Soc.

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An Efficient Synthesis of 6‐oxa‐spiro[3.4]octan‐1‐one Derivates Through 3‐diazochroman‐4‐one and Alkene

Xiao

Zhang

et al. 2018

Adv Synth Catal

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Spiro[2,bicyclo [4.2.0]octane]-7'-one with fused and spirocyclic oxygen-containing rigid skeleton structure is obtained via Wolff rearrangement and cycloaddition with good yields. Then Spiro[2,2-dimethyl-benzofuran,hexahydro-isobenzofuran]-7'-one is synthesized by further Baeyer-Villiger oxidation. These two kinds of products have a special fused and spirocyclic oxygen-containing rigid skeleton structure and are reported by our group.

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ChemInform Abstract: SYNTHESIS OF QUASSINOIDS. 5. CONVERSION OF D‐RING SECO DERIVATIVES OF CHOLIC ACID TO Δ‐LACTONES

Dias¹,

Ramachandra²

1978

Chemischer Informationsdienst

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Synthesis of quassinoids. 5. Conversion of D-ring seco derivatives of cholic acid to .delta.-lactones

Cited by 10 publications

References 10 publications

Ring transformation equilibrium (bond switch) in 5-(2-aminovinyl)isothiazole system via hypervalent sulfurane. Synthesis, structure determination, and kinetic study

Ring transformation equilibrium (bond switch) in 5-(2-aminovinyl)isothiazole system via hypervalent sulfurane. Synthesis, structure determination, and kinetic study

An Efficient Synthesis of 6‐oxa‐spiro[3.4]octan‐1‐one Derivates Through 3‐diazochroman‐4‐one and Alkene

ChemInform Abstract: SYNTHESIS OF QUASSINOIDS. 5. CONVERSION OF D‐RING SECO DERIVATIVES OF CHOLIC ACID TO Δ‐LACTONES

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