Keiichiro Fukumoto

A novel o-quinodimethane strategy for an active metabolite of vitamin D3. A total synthesis of 25-hydroxy windaus-grundmann ketone

Abstract A highly diastereoselective total synthesis of 25-hydroxy Windaus-Grundmann ketone (2) was achieved via a novel regiocontrolled Cue5f8C bond formation by an intramolecular epoxide ring opening reaction of the bissulfonyl epoxide (19) as a key step, which was derived stereoselectively by the thermolysis of olefinic benzocyclobutene (8) as a key step.

A novel strategy for the enantioselective synthesis of the steroidal framework using cascade ring expansion reactions of small ring systems-asymmetric total synthesis of (+)-equilenin

Abstract Enantioselective synthesis of (+)-equilenin ( 1 ) utilizing a novel strategy is described. The key steps are two cascade ring expansion reactions of small ring systems; 1) chiral (salen)Mn III complex-catalyzed cascade reaction of cyclopropylidene; 2) Pd II -mediated cascade reaction of the cyclobutanol.

Pd2-promoted cyclization in linear triquinane synthesis total synthesis of (±)-hirsutene

Abstract A sequence leading from trans -6-methyl-3-cyclohexenecarboxylic acid ( 3 ) to the cis, anti, cis - tricyclopentane ring system of the hirsutanes is described in which the key step utilizes an acid catalyzed intramolecular conjugate addition ( 5→6a ) and a Pd 2+ -promoted highly stereocontrolled cyclization ( 7→8 ).

The first example of asymmetric dihydroxylation of cyclopropylidene derivatives—An enantioenriched formal total synthesis of (−)-filiformin

Abstract The first example of asymmetric dihydroxylation (AD) of the cyclopropylidene derivatives 4a∼e followed by enantiospecific 1,2-rearrangement of the resulted diols 5a∼e to give the optically active cyclobutanones 7∼e was reported. The synthesis of 7e constitutes an enantioenriched formal total synthesis of (−)-filiformin (8).

1,3-DIPOLAR CYCLOADDITION OF 1-CARBOXYNITRONE : DIFFERENT STEREOSELECTIVITY CAUSED BY SALT EFFECT

Abstract Treatments of 1-carboxynitrone 1 with monosabstituted olefins 2 caused a 1,3-dipolar cycloadditions to give cis-isoxazolidines 3 with high stereoselection. On the other hand, reactions of 1 with olefins in the presence of triethylamine afforded trans-isomers 4 predominantly.

An efficient synthesis of the naphthalene moiety of neocarzinostatin chromophore

Methyl 2-hydroxy-7-methoxy-5-methyl-1-naphthalenecarboxylate, the methanolysis product of neocarzinostatin chromophore, was efficiently synthesized from 1-cyano-5-methoxy-3-methylbenzocyclobutene employing an electrocyclic reaction of E-o-quinodimethane as the key step.

A simple total synthesis of (±)-spirojatamol and (±)-erythrodiene via intramolecular 1,3-dipolar cycloaddition

An efficient synthesis of spirobicyclic sesquiterpenes, (±)-spirojatamol 1 and (±)-erythrodiene 2, using an intramolecular 1,3-dipolar cycloaddition as the pivotal step is described.

Stereocontrolled intramolecular michael-aldol reaction mediated with bu2botf and (tms)2nh

Abstract Treatment of keto-esters 1–5 with Bu 2 BOTf and (TMS) 2 NH caused a tandem Michael-aldol reaction to give polycyelic cyclobutanes 6–10 with high stereoselection. It was proved that the reaction was accelerated by the addition of Bu 4 NI

Preparation of chiral building blocks for synthesis of Aconitium alkaloids

Abstract Treatment of meso -diols 3 and 6 with CCL and vinyl acetate without solvent produced the AE part of Aconitium alkaloids 2 and 7 in 68% and 75% yields, respectively, with > 96% e.e. Quantitative formations of their MTPA esters 4 and 8 were achieved by reaction with MTPA in the presence of DCC and DMAP in ClCH 2 CH 2 Cl.

A mild oxidative transformation of nitro compounds into ketones by tetrapropylammonium perruthenate

Oxidation of secondary nitro compounds with a catalytic amount of ntetrapropylammonium perruthenate in the presence of nN-methylmorpholine N-oxide, silver(I) acetate, npotassium carbonate and 4 A molecular sieves provides the ncorresponding ketones in moderate to good yields.