938-07-8Relevant academic research and scientific papers
High trans-2-Decalones by Photoredox Catalyzed β-Isomerization
Sombret, Juliette,Quintaine, Julie,Biremond, Tony,Barnes, Quentin,de Saint-Laumer, Jean-Yves,Saudan, Lionel
, (2021/12/03)
The synergistic combination of three catalytic processes – photoredox, enamine and hydrogen atom transfer (HAT) catalysis – enabled the β-isomerization of 2-decalones towards the thermodynamically most stable trans-isomers. A library of iridium (III) complexes and organic dyes were screened in combination with cyclic amines and thiols which after optimization gave the desired trans-2-decalones with high trans/cis ratios of 60 : 40 up to 98 : 2.
Syn-axial steric and counter-ion coordination factors in the methylation of 6-membered cyclic esters
Balasubrahmanyam,Jayaraj
, p. 1098 - 1110 (2007/10/03)
It was found in an earlier study that one (A) of the four possible configurational isomers of trimethyl 1-methylcyclohexane-1,2,3-tricarboxylate yields, in regiospecific and highly stereospecific manner, trimethyl trans, meso 1,2-dimethylcyclohexane-1,2,3-tricarboxylate on exposure to the methylation condition of treatment with tritylsodium (ether)/methyl iodide. Isomer A changes to isomer C via enolate formation unexpectedly slowly even though what was needed for the transformation was only a ring inversion. Equally unexpectedly, it was found in an independent experiment that an (x-enolate is not formed at all directly from C on treatment with tritylsodium. The role that coordination of counterion (Na+) may play in the first case and manner in which 1,3-syn axial steric effect may operate in the second was sought to be tested by employing methyl 9-ethoxycarbonyl- and methyl 9-methyl-trans-decalin-2-carboxylates as test systems having no possibility of ring-inversion. The 9-methyl system, analogue of C, did not form an α-enolate ion, as expected. On the other hand, the 9-ester, analogue of A, readily formed an enolate that does not undergo methylation under conditions when A does. It did undergo the reaction, practically non-stereoselectively however, when the strong de-coordinating agent hexamethyl phosphoric triamide was added before the addition of methyl iodide.
[4 + 3] cycloadditions of cyclic oxyallyls and cyclic 1,3-dienes
Jin, Shu-Juan,Choi, Jong-Ryoo,Oh, Jonghoon,Lee, Dongha,Cha, Jin Kun
, p. 10914 - 10921 (2007/10/03)
The [4 + 3] cycloaddition of the oxyallyl intermediates, derived from 2-chlorocyclohexanone and related compounds, to cyclic 1,3-dienes under the F?hlisch conditions (Et3N in CF3CH2OH) has been examined to assess its scope
Palladium Assisted Transfer Hydrogenation of Cyclic α,β-Unsaturated Ketones by Ammonium Formate
Rao, H. Surya Prakash,Reddy, K. Subba
, p. 171 - 174 (2007/10/02)
α,β-Unsaturated ketones can be hydrogenated conveniently under catalytic hydrogenation conditions using ammonium formate / Pd-C (10percent) in refluxing methanol.
A CONVENIENT PROCEDURE FOR DISSOLVING METAL REDUCTIONS
Markgraf, J. Hodge,Staley, Stuart Waugh,Allen, Timothy R.
, p. 1471 - 1478 (2007/10/02)
Alicyclic α,β-unsaturated ketones react with lithium in ethylenediamine, followed by Jones oxidation, to give cyclic ketones in good yield.The stereoselectivity at the β position parallels that observed with lithium in liquid ammonia.
Enzymes in organic synthesis. 37. Preparation and characterization of potential decalindione substrates of horse liver alcohol dehydrogenase
Jones, J. Bryan,Dodds, David R.
, p. 2397 - 2404 (2007/10/02)
The preparations of ten decalindiones for investigation as substrates of horse liver alcohol dehydrogenase are reported.The structure characterizations include clarifications of some ambiguities in the decalin literature.
Stereospecific Photoreduction of Polycyclic α,β-Unsaturated Ketones
Chan, Alexander C.,Schuster, David I.
, p. 4561 - 4567 (2007/10/02)
The photolysis of 4a-methyl-4,4a,9,10-tetrahydro-2(3H)-phenenthrone (1) in isopropyl alcohol (i-PrOH) is found to give lumikeone rearrangement product 5 and reduction product 8 via the enone triplet ?,?* excited state.Other reduction products 6,7, and 9, arise from the triplet n,?* excited state.The lower limit of the energy of the triplet state En,?* is estimated to be ca. 67 kcal/mol above the ground state and that of the relaxed triplet ?,?* excited state is ca. 61 kcal/mol.Reduction of the C=C bond on the enone chromophore from both excited states is stereospecific, with the twisted ?,?* triplet leading exclusively to cis-fused bicyclic ketone and the planar n,?* triplet to the trans fused isomer.The results from the photolysis of 4a-methyl-4,4a,5,6,7,8-hexahydro-2(3H)-naphthalenone (4) are consistent with these findings.
NOUVELLE METHODE D'ANNELATION PAR L' INTERMEDIAIRE DE DICETONES-1,5
Duhamel, Pierre,Poirier, Jean-Marie,Tavel, Gilbert
, p. 43 - 46 (2007/10/02)
A new method for six-membered ring annelation is described which involved reaction of hemiacetal vinylogs 1 with silyl enol ethers 2 in the presence of a Lewis acid.
SELECTIVITE DE LA REDUCTION D'α-ENONES POLYCYCLIQUES PAR LES BOROHYDRURES: EFFET DE L'ADDITION DE TETRAMETHYL-ETHYLENEDIAMINE AU BOROHYDRURE DE TETRABUTYLAMMONIUM
D'incan, E.,Loupy, A.,Maia, A.,Seyden-Penne, J.,Viout, P.
, p. 2923 - 2927 (2007/10/02)
Δ1,9octalone, Δ1,9-10-methyl octalone and testosterone were reduced by NBu4BH4, alone or in the presence of tetramethylethylenediamine (TMEDA), in THF and in toluene.With TMEDA, the first step of the reduction is the regioselective 1,4 attack by BH4(1-) which leads either to the saturated ketones or to the corresponding saturated alcohols.The results observed under different conditions were interpreted by the intervention of various reductive species: diborane, enoxyborohydrides in the absence of TMEDA, amine-borane in its presence.
