6704-77-4Relevant academic research and scientific papers
Sulfur-ylide-mediated synthesis of functionalized and trisubstituted epoxides with high enantioselectivity; Application to the synthesis of CDP-840
Aggarwal, Varinder K.,Bae, Imhyuck,Lee, Hee-Yoon,Richardson, Jeffery,Williams, David T.
, p. 3274 - 3278 (2007/10/03)
Benzyl and substituted allyl sulfonium salts react with a broad range of simple and functionalized aldehydes and ketones to give epoxides with high diastereoselectivity and high enantioselectivity (see scheme). The process has been applied to a short synthesis of the phosphodiesterase-IV inhibitor CDP-840. R1, R2 = hydrogen, alkyl, alkenyl, alkynyl, aryl, or pyridyl.
New mechanistic aspects on the catalytic transformation of vinylthiiranes to mono and disubstituted 3,6-dihydro-1,2-dithiins by tungsten pentacarbonyl monoacetonitrile
Lupton, David W,Taylor, Dennis K
, p. 4517 - 4527 (2007/10/03)
Various alkyl and aryl mono- and disubstituted 3,6-dihydro-1,2-dithiins have been synthesised from their corresponding vinylthiiranes exploiting Adams' tungsten pentacarbonyl monoacetonitrile catalytic transformation. New conclusions pertaining to the rate determining step, the sensitivity of the process to precursor sterics and electronics, and the nature of various reaction intermediates are highlighted.
Catalytic asymmetric synthesis of epoxides from aldehydes using sulfur ylides with in situ generation of diazocompounds
Aggarwal, Varinder K.,Alonso, Emma,Hynd, George,Lydon, Kevin M.,Palmer, Matthew J.,Porcelloni, Marina,Studley, John R.
, p. 1430 - 1433 (2007/10/03)
A practical, general, and convergent to epoxides with control of the relative and absolute stereochemistry has been achieved by generating the reactive intermediate (the diazo compound) in situ from tosylhydrazone salts (see scheme, PTC = phase-transfer catalyst, Ts = toluene-4-sulfonyl). High yields (58-82%), high d.r. (88:12-98:2), and high ee values (87-94%) have been obtained using a new class of stable chiral sulfides at low catalyst loading (5 mol%) and [Rh2(OAc)4] (0.5 mol%).
Oxyanionic Substituent Effect on the C-H Insertion of Carbenes. Reaction of Alkoxides with Dichlorocarbene and Chlorophenylcarbene
Harada, Toshiro,Akiba, Eiji,Oku, Akira
, p. 2771 - 2776 (2007/10/02)
The lithium alkoxides of benzylic, allylic, and simple alkyl alcohols were allowed to react with chloroform in the presence of t-BuOLi in THF-hexane to give, in 32-91percent yields, dichloromethylcarbinols, which were produced by the insertion of dichlorocarbene into the α C-H bond of alkoxides but not by the Wittig rearrangement of carbanions of alkyl dichloromethyl ethers.The enhanced reactivity toward dichlorocarbene of the α C-H bond of alkoxides was clearly demonstrated by the high selectivity of the insertion.The potassium alkoxides of a series of analogous alcohols reacted analogously with benzal chloride in the presence of t-BuOK in THF to give the corresponding substituted oxiranes (16-79percent); e.g., the reaction of potassium benzyl oxide gave 2,3-diphenyloxirane (79percent) as a mixture of stereoisomers (trans:cis = 1.0).With 2-phenethoxide, n-octyl oxide, or 2-methoxyethoxide, the corresponding dialkyl acetals of benzaldehyde were also formed in 9, 6, and 6percent yield, respectively, and their formation is explained in terms of nucleophilic attack of alkoxide on chlorophenylcarbene.With trans-crotyl oxide or 2-phenetoxide, 1,3-diphenylpropan-1-one(33percent) and 1-phenylpent-3-en-1-one (6percent) were produced, respectively, as byproducts through the isomerization of the primary product oxiranes.Oxiranes were produced by the insertion of chlorophenylcarbene into the α C-H bond of alkoxides followed by the cyclization of the intermediate 1-substituted 2-chloro-2-phenethyl alkoxide.These reactions provide us with new preparative methods of synthetically useful dichloromethyl carbinols and oxiranes.
