14727-58-3Relevant academic research and scientific papers
Pseudohelical and helical primary structures of 1,2-spiroannelated four- and five-membered rings: Syntheses and chiroptical properties
Widjaja, Tien,Fitjer, Lutz,Pal, Aritra,Schmidt, Hans-Georg,Noltemeyer, Mathias,Diedrich, Christian,Grimme, Stefan
, p. 9264 - 9277 (2007)
(Chemical Equation Presented) The pseudohelical hydrocarbons (R)-6, (S)-7, and (R)-8 and the helical hydrocarbon (P)-9, formally derived from the helical hydrocarbon (P)-4 by stepwise replacement of each of the four-membered rings by a five-membered ring,
Highly regioselective alkylation at the more hindered α-site of unsymmetrical ketones by use of their potassium enolates. A comparative study with lithium enolates
Quesnel, Yannick,Bidois-Sery, Laure,Poirier, Jean-Marie,Duhamel, Lucette
, p. 413 - 415 (2007/10/03)
Alkylation of regioisomeric potassium enolates 4 and 6 obtained from corresponding silyl enol ethers 2 and 3 occurs at the most substituted site affording ketones 8. Alkylation of corresponding lithium enolates 5 and 7 occurs at the expected site affording ketones 8 or 9. As an application the one pot synthesis of spiroketones 13 from silyl enol ethers 12 is described.
Cyclobutyl phenyl sulfoxide and (SR)-cyclobutyl p-tolyl sulfoxide: New reagents for the spiroannelation of cyclopentanone
Fitjer, Lutz,Schlotmann, Werner,Noltemeyer, Mathias
, p. 4985 - 4988 (2007/10/02)
Cyclobutyl phenyl sulfide 2, cyclobutyl phenyl sulfoxide 3 and (SR)- cyclobutyl p-tolyl sulfoxide (SR)-8 have been synthesized and used for the spiroannelation of cyclopentanone. In the most effective sequence, lithiated 3 is added to ketones with formation of β-hydroxy sulfoxides 4a-g, which are ring enlarged and hydrolyzed to cyclopentanones 6a-e and sulfanylcyclopentene 6f, respectively, after reduction to β-hydroxy sulfides 5a-f. In an asymmetric version using (SR)-8, partial racemization during ring enlargement was observed.
SPIRO KETONE SYNTHESIS VIA LITHIUM-IODINE EXCHANGE OF α-(ω-IODOALKYL) ESTERS
Does, T. van der,Klumpp, G. W.,Schakel, M.
, p. 519 - 520 (2007/10/02)
The title reaction (2 eq. of t-BuLi, -100 deg C) provides a new route to five- and six-membered ring ketones and has permitted the synthesis of two spiro ketones that were inaccessible by conventional methods.
Five-membered ring spiro-annulation via thermal rearrangement of enol silyl ethers of 2-(cyclopropylmethylene)cycloalkanones. A formal total synthesis of some spirovetivane-type sesquiterpenoids
Piers, Edward,Lau, Cheuk Kun,Nagakura, Isao
, p. 288 - 297 (2007/10/02)
Treatment of the 2-(iodomethylene)cycloalkanones 10 and 11 with lithium (phenylthio)(cyclopropyl)cuprate provided good yields of the corresponding β-cyclopropyl enones 12 and 13, respectively.Thermolysis of the latter substances produced relatively poor yields of the desired spiro-annulation products 14 and 15.However, conversion of 12 and 13 into the corresponding enol silyl ethers 24 and 25, followed by thermal rearrangement of the latter materials and acid hydrolysis of the resulting products, provided synthetically useful yields of the spiro enones 14 and 15.Cuprous iodide-catalyzed addition of methyl magnesium iodide to 2-cyclohexen-1-one, followed by trapping of the resultant enolate anion with cyclopropanecarboxaldehyde, provided the ketols 38, which could be converted into the mixture of enol silyl ethers 34 and 35.Thermal rearrangement of the latter substances gave, after acid hydrolysis of the crude thermolysate, the spiro enones 42 and 43 in a ratio of ca. 2.5 : 1 (57 percent yield).Treatment of 42 with methyllithium in ether gave the tertiary alcohols 44 and 45 (ratio ca. 4 : 1).Hydroboration (disiamylborane, tetrahydrofuran; H2O2, NaOH) of 44, followed by oxidation of the resultant diol 46 with pyridinium chlorochromate, provided the ketol 47.A similar sequence of reactions converted the olefinic alcohol 45 into the ketol 49.Dehydration (p-toluenesulfonic acid in benzene) of 47 gave the spiro enones 28 and 48, in a ratio of ca. 9 : 1.Compound 28, also prepared previously from the ketol 49, had been converted earlier into the spirovetivane-type sesquiterpenoids (+/-)-α-vetispirene (29), (+/-)-vetivone (30), (+/-)-hinesol (31), (+/-)-hinesol acetate (32), and (+/-)-agarospirol (33).
A New Spiro-annelation Procedure: Intramolecular Decarboxylative Alkylation of β-Keto-esters
Eilerman, Robert G.,Willis, Brian J.
, p. 30 - 32 (2007/10/02)
A new intramolecular decarboxylative alkylation route to spirocyclic ketones, and its application to the synthesis of (+/-)-β-vetivone and (+/-)-β-vetispirene are described.
