We have found that an organic molecule as simple as p-anisaldehyde efficiently catalyzes the intermolecular atom-transfer radical addition (ATRA) of a variety of haloalkanes onto olefins, one of the fundamental carbon-carbon bond-forming transformations in organic chemistry. The reaction requires exceptionally mild reaction conditions to proceed, as it occurs at ambient temperature and under illumination by a readily available fluorescent light bulb. Initial investigations support a mechanism whereby the aldehydic catalyst photochemically generates the reactive radical species by sensitization of the organic halides by an energy-transfer pathway.

An innovative two stage liquid–liquid biphasic homogeneous protocol for the asymmetric organocatalytic aldol reaction is proposed, based on the use of the cis‐ion‐tagged proline 8 dissolved in the liquid film of a multilayered ionic liquid covalently bonded to silica gel 4. The resulting catalytically active material 9 is first soaked with cyclohexanone in the presence of water, resulting in a semi‐transparent gel, then the aldehyde is added and the mixture stirred at RT. In the first stage, 4 acts as a catalyst reservoir that delivers 8 to the cyclohexanone phase allowing the reaction to take place homogeneously. In the second stage, cyclohexanone is removed under vacuum and the resulting slurry is extracted with anhydrous diethylether. Now 4 acts as a catalyst sponge, redissolving 8. Product extraction is extremely selective; no trace of catalyst is detected in the product‐containing phase, and 9 can be easily reused several times with high cumulative productivity values (up to 523).

A new Michael-Michael cascade reaction between 2-(2-oxoindolin-3-ylidene)acetic esters 1 and nitroenoates 2, catalyzed by bifunctional thioureas, is investigated. The combination of the two Michael reactions results in a novel and facile [4+2] or [3+2] spiroannulation process, which is characterized by the following features: 1) two carbon-carbon bonds and four stereocenters, including a quaternary spiro carbon, are formed under mild conditions; 2) an unprecedented and stereochemically defined substitution pattern on the spirocarbocyclic unit is obtained; 3) the double-bond configuration of the donor-acceptor nitroenoate 2 determines the absolute configuration of the spiro center, whereas the remaining stereocenters are formed under control of the catalyst. The effect on the final stereochemical outcome of structural variations of each starting material, catalyst, and experimental conditions is analyzed in detail. In particular, the use of specifically designed chiral nitroenoates enables diverse polyfunctional spirocyclohexane derivatives containing six consecutive stereogenic centers to be constructed. To our knowledge, this is the first asymmetric organocatalytic strategy enabling both five- and six-membered β-nitro spirocarbocyclic oxindoles.

We have found that an organic molecule as simple as p-anisaldehyde efficiently catalyzes the intermolecular atomtransfer radical addition (ATRA) of a variety of haloalkanes onto olefins, one of the fundamental carbon-carbon bondforming transformations in organic chemistry. The reaction requires exceptionally mild reaction conditions to proceed, as it occurs at ambient temperature and under illumination by a readily available fluorescent light bulb. Initial investigations support a mechanism whereby the aldehydic catalyst photochemically generates the reactive radical species by sensitization of the organic halides by an energy-transfer pathway.Atom-transfer radical addition (ATRA) [1] to alkenes provides a clear demonstration of the utility of radical reactivity in organic synthesis. The chemistry, pioneered by Kharasch almost 70 years ago, [2] has evolved to become an atomeconomical and effective way to functionalize easily available olefinic substrates, mainly thanks to the contributions from the groups of Curran, [1b, 3] Oshima, [4] and Renaud. [5] The addition of an organic halide across a carbon-carbon double bond generates a new CÀC and CÀX bond (X = halogen) in a single operation. This reactivity is also at the heart of atomtransfer radical polymerization (ATRP) processes. [1a,c] ATRA proceeds through a radical chain propagation mechanism (Figure 1 a), and the formation of the radicals from alkyl halides classically requires stoichiometric amounts of initiators, such as organotin reagents, [3] triethyl borane, [4] or potentially explosive oxidants, [2] and high reaction temperatures. Recently, metal-mediated catalysis, [6] including metalbased photoredox catalysis driven by visible light, [7] has further expanded the potential of the ATRA technology.However, we still need a suitable approach for generating radical intermediates under mild reaction conditions which avoids expensive transition-metal catalysts or toxic reagents.Herein, we describe a strategy that addresses this gap in synthetic methodology. Motivated by our interest in devising metal-free photochemical processes, [8] we have found that an organic molecule as simple as p-anisaldehyde (1 a) can efficiently catalyze the intermolecular ATRA of a variety of haloalkanes (2) onto olefins (3; Figure 1 b). The chemistry requires irradiation from a household 23 W compact fluorescent light (CFL) bulb to proceed, and ambient temperature is sufficient for achieving functionalized olefins (4) with synthetically useful results. Initial investigations support a mechanism whereby the aldehydic catalyst generates the reactive radical species by energy transfer [9] to the haloalkane substrates. Although the utility of UV-absorbing organic chromophores as triplet photosensitizers has been wellestablished for decades, [10] applications of triplet sensitization induced by readily available CFL light sources have found limited use in synthetic chemistry so far. [11] Our initial explorations toward an ATRA protocol under mild reaction conditions focused on the...

An efficient and highly enantioselective Michael addition of nitroalkanes to 3-ylidene oxindoles is described, mediated by thiourea-based bifunctional organocatalysts. The stereochemistry at C(α) and C(β) centers is perfectly controlled, and the intermediate C-3 enolate is trapped with a second Michael acceptor. The developed one-pot three-component consecutive reactions generate up to four contiguous stereocenters, including the C-3 all-carbon quaternary center, in a perfectly defined configuration. The conversion of the β-nitro oxindole into the corresponding β-amino derivative discloses synthetically useful transformations, exploitable to generate pharmaceutically attractive molecular targets.