Concise Stereoselective Synthesis of (−)‐Podophyllotoxin by an Intermolecular Iron(III)‐Catalyzed Friedel–Crafts Alkylation

Synthesis of enantiomerically enriched indolines and tetrahydroisoquinolines from (S)-amino acid-derived chiral carbocations: an easy access to (3S,4R)-demethoxy-3-isopropyl diclofensine

Enantiomerically enriched indolines and tetrahydroisoquinolines were synthesized in high yields from easily accessible (S)-amino acid-derived chiral carbocations.

Asymmetric synthesis towards doxanthrine, a dopamine D1 full agonist

First asymmetric synthesis of towards doxanthrine is accomplished with high diastereo- and enantioselectivity from β-aryloxyamino acid derived from D-serine.

Enantioselective synthesis of tatanans A-C and reinvestigation of their glucokinase-activating properties

The tatanans are members of a novel class of complex sesquilignan natural products recently isolated from the rhizomes of Acorus tatarinowii Schott plants. Tatanans A, B and C have previously been reported to have potent glucokinase-activating properties that exceed the in vitro activity of known synthetic antidiabetic agents. Here, using a series of sequential [3,3]-sigmatropic rearrangements, we report the total synthesis of tatanan A in 13 steps and 13% overall yield. We also complete a concise enantioselective total synthesis of more complex, atropisomeric tatanans B and C via a distinct convergent strategy based on a palladium-catalysed diastereotopic aromatic group differentiation (12 steps, 4% and 8% overall yield, respectively). A plausible biosynthetic relationship between acyclic tatanan A and spirocyclic tatanans B and C is proposed and probed experimentally. With sufficient quantities of the natural products in hand, we undertake a detailed functional characterization of the biological activities of tatanans A-C. Contrary to previous reports, our assays utilizing pure recombinant human enzyme demonstrate that tatanans do not function as allosteric activators of glucokinase.

Diastereoselective Friedel-Crafts alkylation of hydronaphthalenes

An efficient and versatile synthesis of chiral tetralins has been developed using both inter- and intramolecular Friedel-Crafts alkylation as a key step. The readily available hydronaphthalene substrates were prepared via a highly enantioselective metal-catalyzed ring opening of meso-oxabicyclic alkenes followed by hydrogenation. A wide variety of complex tetracyclic compounds have been isolated with high levels of regio-, diastereo-, and enantioselectivity.

Syntheses of secocyclolignanes and comparative antioxidative activity between secocyclolignane and the dibenzyl type of lignan

The antioxidative activity of secocyclolignanes was compared with that of the corresponding dibenzyl lignans for the first time. The radical scavenging activity of the secocyclolignanes was weaker than that of the corresponding dibenzyl lignans, the butane diol type showing the highest activity. The butane type of secocyclolignane exhibited the highest antioxidant activity of the unsaturated fatty acid.

Regioselective ruthenium-catalyzed direct benzylations of arenes through C-H bond cleavages

Highly regioselective ruthenium-catalyzed direct benzylations through C-H bond cleavages were accomplished under remarkably mild, nonacidic reaction conditions, for which experimental studies suggested a S(E)Ar-type mechanism not to be operative.