Ni-catalyzed regiodivergent hydrophosphorylation of enynes

A regiodivergent hydrophosphorylation of enynes with phosphites has been developed using earthabundant nickel catalyst.The manipulation of regioselectivity can be achieved by regulating the insertion order of alkyne bonds with(RO)_(2)P(O)-Ni-H or R_(2)P(O)O-Ni-H species,respectively.Under the Ni/Xantphos catalysis,4,1-hydrophosphorylation is selectively obtained while the adding of acid can promote reactions towards 1,2-addition.By employing an additional Pd-H catalysis,2,1-hydrophosphorylation is also an accessible task in one-pot reaction.Mechanistic studies and analysis have also been performed to interpret the origin of the regioselective regulation.This work highlights the arts in accessing different regioisomers by diverting common elementary reaction steps.

Metal-Free Arylsulfonyl Radical Triggered Cascade Cyclization of Phenyl-Linked 1,6-Enynes:Synthesis of 2,3-Dihydro-1H-indenes and 10a,11-Dihydro-10H-benzo[b]fluorines

Aryl sulfonyl radical triggered cascade cyclization of phenyl-linked 1,6-enynes for the synthesis of biologically important indenes containing alkenyl C—X bonds and 10a,11-dihydro-10H-benzo[b]fluorines is presented.In these radical cascade processes,three new chemical bonds,including C—S,C—C,and C—X bonds,and three C—C bonds are formed in one step.The method is attractive and valuable due to its metal-free,mild reaction conditions,broad substrate scope and good functional group tolerance.

Synthesis and Determination of Absolute Configuration of a Divergent Polyhydroxy Enyne Compound

Polyhydroxy enyne compound （＋）-（1＇S, 2R, 3S, 5S, 6S）-5,6-dimethoxy-5, 6-dimethyl- 2-（1＇-hydroxylpropyl-2-ne）-3-vinyl-l,4-dioxane has been synthesized from D-（-）-tartaric acid. A new chiral center was established by nucleophilic addition with 87% de. The modified Mosher＇s method was employed to confirm the absolute configuration of 17, which assigned the S-configuration at the new chiral center.

Total synthesis of a putative yuzurimine-type Daphniphyllum alkaloid C_(14)–epi-deoxycalyciphylline H

One of the largest subfamilies within the famous Daphniphyllum alkaloid family is made up of the yuzurimine-type(or macrodaphniphyllamine-type) alkaloids. Their complex aza-polycyclic caged structures, several contiguous stereogenic centers, and vicinal all-carbon quaternary centers make these alkaloids formidable challenge for synthetic chemists. Recently, synthesis of these alkaloids has received extensive attention from our community. Herein, we wish to report the total synthesis of C_(14)–epideoxycalyciphylline H, a putative member of yuzurimine-type alkaloid subfamily. Key transformations employed in our approach include an intramolecular Prins reaction and a Pd-catalyzed enyne cycloisomerization. In addition, synthesis of a daphnezomine L-type alkaloid, paxdaphnidine A, was also studied.

Copper-catalyzed 1,4-protosilylation and 1,4-protoborylation of enynic orthoesters for synthesis of functionalized 2,3-allenoates

Herein,copper-catalyzed 1,4-protosilylation and 1,4-protoborylation of enynic orthoesters have been developed.The enynic orthoesters as precursors of unstable enynic esters were applied to produce the functionalized 2,3-allenoate products.Meanwhile,the asymmetric 1,4-protosilylation of enynic orthoesters with Ph Me2Si-Bpin was also studied.The chiral monopyridine imidazoline ligand was efficient to provide the asymmetric 1,4-protosilylation products with high enantioselectivity.

Diastereodivergent Hydrosilylative Enyne Cyclization Catalyzed by N-Heterocyclic Carbene-Ni(o)

Catalytic diastereodivergent hydrosilylative enyne cyclization with high generality and broad scope was achieved using electronic ac-tivated N-heterocyclic carbene-Ni(O)as a catalyst and R_(3)SiH as silane(IPr^(Cl),syn-:anti-selectivity from up to 98:2 to 7:93 by Z=0,NH vs.NMs,R^(1)=n-pentyl).Heterocycles bearing homoallylsilane rather than vinylsilane was obtained chemoselectively.The undesired yet highly competitive reactivity was suppressed,like direct hydrosilylation of alkene and alkyne concurrently.Optionally,the homoallylsilane products could be reduced further in one-pot using IPr^(Me) as ligand and(EtO)_(3)SiH as silane under otherwise the same standard condition as the above,offering practical access to additional stereocenters and more diverse product structures from enynes.

Mechanistic investigation of zwitterionic MOF-catalyzed enyne annulation using UNLPF-14-Mn^(Ⅲ) as catalyst

Hybrid quantum mechanics/molecular mechanics calculations were performed to elucidate how[Mn^(Ⅲ)porphyrin]^(+X−)-based metal-organic frameworks(MOFs)catalyze the[2+1]cycloisomerization of enynes and why zwitterionic MOFs exhibit strong activity in Lewis acid catalysis.The calculations showed that zwitterionic MOFs have a“pure cationic active center”leading to a concerted nucleophilic attack pathway with lower barriers.In contrast,metals with coordinating anions have reduced electrophilicity,resulting in a stepwise radical-type pathway with much higher barriers.Further calculations showed the nature of catalysis was strongly depended on the charge on the anion ligand.A good linear relationship between the NPA charge and barrier was found,and verified by 73 anions with small derivations,which presents a universal adaptive character for various coordinated anions.

An Unexpected Reaction of Allylic Propynoate under Palladium(II) Catalysis

Palladium (II) catalyzed reactions of allyl propynoate in the presence of excess halide ions with or without allyl halide or acrolein were studied, yielding (E)-3-halo-2-allyl-acrylic acid as the sole product. A mechanism involving halopalladation, carbopalladation, ring opening and β-heteroatom elimination was proposed and was further justified by the reaction with deuterated substrate.