Search

Highly substituted cyclic β-alkoxyvinyl phosphonates underwent thermal [2+2] cycloaddition with activated ketenes to afford bicyclic phosphonates. Fragmentation of the central polarized bond of this bicyclic system occurred readily upon treatment with zinc in acetic acid, to give rise to ring expanded products. This method provides access to cycloheptane-1,3-diones substituted at the 4-position with a phosphonate group.

The reaction of ketophosphonium ylides with dimethyl acetylenedicarboxylate in aprotic solvents gave mixtures of Z and E alkene products. Under protic conditions the initial Michael adduct was protonated and gave Z and E isomers of the alkene product as well. Depending on the alkyl group of the ketoylide, different product ratios were seen.

Substituted seven and eight membered rings were formed from cyclopentanone and cyclo-hexanone via cycloadditions of pyrrolidine enamines with alkynyl phosphonates. This procedure provides straightforward access to functionalized medium sized rings that could be further manipulated in the synthesis of a number of natural products.

Alkylation of cyclic β-oxophosphonates using the ion pair extractive-phase transfer catalysis method was studied using 2-(diethoxyphosphinyl)cyclohexanone as the model compound. Unlike related phosphonic acid derivatives, the cyclic β-oxophosphonates exhibited ambident character under phase transfer conditions when dichloromethane was used as the solvent. Carbon alkylation was most effective when activated and sterically less demanding alkyl halides were utilized

Substituted seven and eight membered rings were formed from cyclopentanone and cyclo-hexanone via cycloadditions of pyrrolidine enamines with alkynyl phosphonates. This procedure provides straightforward access to functionalized medium sized rings that could be further manipulated in the synthesis of a number of natural products.

The reaction of ketophosphonium ylides with dimethyl acetylenedicarboxylate in aprotic solvents gave mixtures of Z and E alkene products. Under protic conditions the initial Michael adduct was protonated and gave Z and E isomers of the alkene product as well. Depending on the alkyl group of the ketoylide, different product ratios were seen.

Michael reaction of phosphonate stabilized anions with activated alkenes and alkynes results in 1,4-addition, diastereoselective Robinson annulation, or (n+ 2) ring enlargement reactions.

Acid halides are known to be reductively coupled with aldehydes and ketones in the presence of samarium diiodide to generate α-hydroxy ketones. Low yields coupled product are obtained due to the competitive process of tetrahydrofuran attack on the acid chloride. This competitive reaction can be avoided and yields improved by preparation of samarium diiodide in acetonitrile.

A variety of β-alkoxyvinylphosphonium bromides were prepared and reacted with sodium ethoxide and dimsyl anion to generate good yields of phosphine oxides 3 rather than the previously reported ylide 4.

Alkylation of cyclic β-oxophosphonates using the ion pair extractive-phase transfer catalysis method was studied using 2-(diethoxyphosphinyl)cyclohexanone as the model compound. Unlike related phosphonic acid derivatives, the cyclic β-oxophosphonates exhibited ambident character under phase transfer conditions when dichloromethane was used as the solvent. Carbon alkylation was most effective when activated and sterically less demanding alkyl halides were utilized

(PBr3) [7789-60-8] Br3P (MW 270.67) InChI = 1S/Br3P/c1-4(2)3 InChIKey = IPNPIHIZVLFAFP-UHFFFAOYSA-N (Cu2Br2) [7787-70-4] Br2Cu2 (MW 286.90) InChI = 1S/2BrH.2Cu/h2*1H;;/q;;2*+1/p-2 InChIKey = OFOWYKFLGFHYJJ-UHFFFAOYSA-L (Zn) [7440-66-6] Zn (MW 65.39) InChI = 1S/Zn InChIKey = HCHKCACWOHOZIP-UHFFFAOYSA-N (conversion of enediols into 1,3-dienes) Physical Data: see entries for Phosphorus(III) Bromide, Copper(I) Bromide, and Zinc.

(POCl3) [10025-87-3] Cl3OP (MW 153.32) InChI = 1S/Cl3OP/c1-5(2,3)4 InChIKey = XHXFXVLFKHQFAL-UHFFFAOYSA-N (ZnCl2) [7646-85-7] Cl2Zn (MW 136.29) InChI = 1S/2ClH.Zn/h2*1H;/q;;+2/p-2 InChIKey = JIAARYAFYJHUJI-UHFFFAOYSA-L (powerful Lewis Acid used in Friedel–Crafts reactions to prepare xanthones,1 benzophenones,2 coumarins,3 and chromanones;4 phosphorylation of alcohols5) Physical Data: see entries for Phosphorus Oxychloride and Zinc Chloride. Handling, Storage, and Precautions: in most cases, freshly fused ZnCl2 must be used for the best results. See Phosphorus Oxychloride for potential hazards.

Highly substituted cyclic β-alkoxyvinyl phosphonates underwent thermal [2+2] cycloaddition with activated ketenes to afford bicyclic phosphonates. Fragmentation of the central polarized bond of this bicyclic system occurred readily upon treatment with zinc in acetic acid, to give rise to ring expanded products. This method provides access to cycloheptane-1,3-diones substituted at the 4-position with a phosphonate group.

Michael reaction of phosphonate stabilized anions with activated alkenes and alkynes results in 1,4-addition, diastereoselective Robinson annulation, or (n+ 2) ring enlargement reactions.

Stereoselective rearrangement of cis-5-(4-methoxybenzyl)-spiro[5,2]-octan-4-ol cis-1 in acidified THF-90% H 2 O 2 affords 9-oxabicyclo[6.2.1]nonyl hydroperoxides 7 and 8 which are converted to medium-ring, keto-butyrolactones 2 and 3.

Ketones are readily spiroannelated by 2-chloroethyldimethyl sulfonium iodide 1 in the presence of t-butoxide anion in t-butanol. The procedure affords a simple one step -spirocyclopropanation of ketones in good yields.

Rearrangement of spiro[5,2]octan-4-ol, 1, in acidified THF-H2O2 is a selective process in which substitution occurs with retention of configuration and ring-expansion with inversion of the carbinyl center.

Synthese des composes du titre par addition de Diels Alder suivie d'une deshydrogenation aromatique