General Cyclopropane Assembly by Enantioselective Transfer of a Redox‐Active Carbene to Aliphatic Olefins
作者:Marc Montesinos‐Magraner、Matteo Costantini、Rodrigo Ramírez‐Contreras、Michael E. Muratore、Magnus J. Johansson、Abraham Mendoza
DOI:10.1002/anie.201814123
日期:2019.4.23
group in this reagent enhances the reactivity and selectivity of geminal carbene transfer. This effect allowed the asymmetric cyclopropanation of various olefins, including unfunctionalized aliphatic alkenes, that enables the three‐step total synthesis of (−)‐dictyopterene A. This unified synthetic approach delivers high enantioselectivities that are independent of the stereoelectronic properties of the
Mercury in organic chemistry. 20. Alkylation of organomercurials via organocopper reagents
作者:R.C. Larock、D.R. Leach
DOI:10.1016/s0040-4039(01)81925-0
日期:1981.1
Aryl-, alkenyl-, and alkylmercurials readily cross-couple with primary and secondary alkyl- and alkenylcuprate reagents to provide the first truly general method for the alkylation of a wide variety of organomercurials.
This invention provides an improved process for producing alkadienes which comprises (1) contacting butadiene or isoprene with a catalyst such as platinum or palladium or a compound of one of said metals in a sulfolane solution, in the presence of a tertiary lower alkylamine formate and at least one phosphine compound of the formula: ##STR1## wherein R.sup.1 is a substituted or unsubstituted C.sub.1-10 hydrocarbon group; R.sup.2 is H, a saturated aliphatic C.sub.1-5 hydrocarbon group, nitro or halogen; m is 1, 2 or 3; n is 0 or 1; x is 0, 1 or 2; y and z each is 0, 1, 2 or 3 (provided that y and z are not zero concurrently and x+y+z=3); A is --SO.sub.3 M wherein M is a cation selected from among H, alkali metals, alkaline earth metals and NH.sub.4 or the formate or an inorganic acid salt of ##STR2## wherein R.sup.3 and R.sup.4 each means a saturated aliphatic C.sub.1-4 hydrocarbon group in an amount of 4 to 200 moles per gram atom of the metal constituting the catalyst to form dimeric alkadienes; (2) separating the reaction mixture into an alkadiene-containing layer and a catalyst-containing layer; and (3) recycling the catalyst-containing layer to the alkadiene production process. The improved process makes it possible to maintain the catalytic activity over a prolonged period of time and to facilitate separation and reuse of the catalyst.
Synthesis of Stable Derivatives of Cycloprop-2-ene Carboxylic Acid
作者:Ni Yan、Xiaozhong Liu、Mahesh K. Pallerla、Joseph M. Fox
DOI:10.1021/jo800042w
日期:2008.6.1
Large-scale syntheses of 3-(cycloprop-2-en-1-oyl)oxazolidinones from acetylene and ethyl diazoacetate are described. Unlike other cyclopropenes that bear a single substitutent at C-3, these compounds are stable to long-term storage. Although the cyclopropene derivatives are unusually stable, they are reactive toward cyclic and acyclic dienes in stereoselective Diels−Alder reactions.
Selected organic peroxides are converted to the corresponding alcohols when contacted with a triorganophosphine in a reaction medium comprising water and an organic solvent miscible with water. In one embodiment, diene polyperoxides are converted to the novel diols.