S. Okamoto, T. Yamada, T. Uchida, N. Kikuta, and Y. Kimura
"Dual-Mode Coupling Copolymerization of Aryl Dialdehyde and Alkynylaldehyde Monomers via Concurrent McMurry Olefination and Alkyne [2+2+2] Cycloaddition Trimerization Reactions Mediated by a Low-Valent Titanium Reagent",
Polymer, 2021, 214, 123344.
[Link]


Kouta Ibe, Takeshi, Yamada, Sentaro Okamoto,
"Synthesis and Vitamin D Receptor Affinity of 16-Oxa Vitamin D3 Analogues", Organic & Biomolecular Chemistry, 2019, 17, 10188-10200.
[Link]


Sentaro Okamoto, Takeshi Yamada, Yu-ki Tanabe, Masaki Sakaia
"Alkyne [2+2+2] Cyclotrimerization Catalyzed by a Low-Valent Titanium Reagent Derived from CpTiX3 (X = Cl, O-i-Pr), Me3SiCl, and Mg or Zn”,
Organomettalics, 2018, 37, 4431-4438.
[Link]


Suchithra Madhavan, Hiromasa Takagi, Shunpei Fukuda and Sentaro Okamoto, "Low−valent titanium−catalyzed deprotection of allyl- and propargyl-carbamates to amines”,
Tetrahedron Letters, 2016, 57, 2074-2077.
[Link]



Sentaro Okamoto, “Synthetic Reactions Using Low-Valent Titanium Reagents Derived from Ti(OP)4 or CpTiX3 (X = O-i-Pr or Cl) in the Presence of Me3SiCl and Mg”,
The Chemical Record, 2016, 16, 857-872

[Link]



Sentaro Okamoto, "Synthetic Reactions Using A Low-Valent Titanium Reagent Ti(OR)4/Me3SiCl/Mg,”
Yuki Gosei Kagaku Kyokaishi, 2014, 72, 382-392.



Generation of A Low-Valent Titanium from Titanatrane and Its Catalytic Reactions: Radical Ring Opening of Oxetanes
[Adv. Synth. Catal. 2013, 355, 2151-2157]



Non-Cp Titanium Alkoxide-Based Homolytic Ring-Opening of Epoxides by An Intramolecular Hydrogen Abstraction in beta-Titanoxy Radical Intermediates
[Chemical Communications, 2011, 47, 7857-7859.]



Ti(O-i-Pr)4/Me3SiCl/Mg-Mediated Reductive Cleavage of Sulfonamides and Sulfonates To Amines and Alcohols
[Organic Letters, 2011, 13, 2626-2629.]
Highlighted in Organic Chemistry Highlights. Highlighted in Organic Chemistry Portal Picked up in ChemInform



McMurry coupling of aryl aldehydes and imino pinacol coupling mediated by Ti(O-i-Pr)4/Me3SiCl/Mg reagent
[Tetrahedron Letters, 2010, 51, 387-390]
Picked up by SYNFACTS(2010, p 346



Two-step allylic carbon insertion between ketone carbonyl and carbons giving a-quaternary a-vinyl ketones
[Tetrahedron Letters, 2008, 49, 6724-6727]
Picked up in ChemInform



Selective Cleavage of Allyl and Propargyl Ethers to Alcohols Catalyzed by Ti(O-i-Pr)4/MXn/M
[Organic Letters, 2007, 9, 773-776]
Picked up in ChemInform



Ti(II)-Mediated domino cyclization of 2-functionalized 1-halo-2,n-enynes (n = 7, 8) to bicyclic compounds
[Tetrahedron Letters, 2006, 47, 7537-7540]
Picked up in ChemInform



Synthesis of N-substituted 2-arylpyrroles by the reaction of (eta2-imine)titanium complexes with 3,3-diethoxypropyne
[Tetrahedron Letters, 2006, 47, 6209-6212]
Highlighted in SYNFACTS(2006, p.1223)



Formation of azatitanacyclopentanes from ene-imines and a Ti(O-i-Pr)4/2i-PrMgX reagent and their synthetic reactions
[Tetrahedron Lettrs, 2004, 45, 9037-9040]
Picked up in ChmeInform

Yu-ki Sugiyama, Masaki Amo, Kouta Ibe, and Sentaro Okamoto
"Synthesis of 2-Aminopyridines via Cobalt-Catalyzed Cycloaddition of Diynes with N-Substituted and N-Unsubstituted Cyanamides",
Adv. Synth. Catal., 2023, 365, 3897-3901. [Link]open access


Yuhsaku Okabe, Takeshi Yamada, and Sentaro Okamoto
"Nickel-Catalysed Cycloaddition Oligomerization of 1,6-Diynes to Medium-Size Cyclic Polyenes",
Polymer Chemistry, 2022, 13, 6075-6172. [Link]


Nana Kikuta, Takahiro Shindo, Yu-ki Sugiyama, Takeshi Yamada
and Sentaro Okamoto
Cobalt-Catalyzed [2 + 2 + 2] Cycloaddition Copolymerization of Diyne and Internal Alkyne Monomers to Highly Branched Polymers
Polymer, 2021, 212, 123133.[Link]


Yu-ki Sugiyama, Shiori Heigozono, Kazuhiro Tamura, Sentaro Okamoto, "Iron-Catalyzed Reductive Metalation–Allylation and Metalative Cyclization of 2,3-Disubstituted Oxetanes and Their Stereoselectivity”,
Synthesis, 2016, 48, 2823-2828.[Link]



Catalytic [2 + 2 + 2] Cycloaddition Polymerization of Diyne–Nitrile Monomers in the Presence of CoCl2-6H2O/Diphosphine/Zn

J. Polym. Sci. A: Polym. Chem. 2016, 54, 345-351..


Iron-Catalyzed Reductive Magnesiation of Oxetanes to Gen-erate (3-Oxidopropyl)magnesium Reagents
Org. Lett. 2014, 16,6278-6281.


Cobalt-Catalyzed Cross Addition of Silylacetylenes to Internal Alkynes,
[J. Org. Chem. 2013, 78, 3583-3591]



From Development of Catalysts for Alkyne and Alkyne/Nitrile [2 + 2 + 2] Cycloaddition Reactions to Their Use in Polymerization Reactions,
[Synlett, 2013, 1044-1060] (Account)



Remarkable Activation of An Alkyne [2 + 2 + 2] Cycloaddition Catalyst, 2-Iminomethylpyridine (Dipimp)/CoCl2-6H2O/Zn, by a Phthalate Additive
[SYNLETT 2012, 23, 2549-2553]



Synthesis of 2,2’-Bipyridines by Transition Metal-Catalyzed Alkyne/Nitrile [2 + 2 + 2] Cycloaddition Reactions
[Review in: Heterocycles, Heterocycles, 2012, 85, 1579-1602.]



Chain-Growth Cycloaddition Polymerization via a Catalytic Alkyne [2 + 2 + 2] Cyclotrimerization Reaction and Its Application to One-shot Spontaneous Block Copolymerization
[J. Am. Chem. Soc. 2011, 133, 9712-9715.]
Highlighted in ACS Noteworthy Chemistry and Selected as SYNFACT of the month



Regioselective Synthesis of Substituted Pyridines and 2,2'-Dipyridines by a Cobalt-Catalyzed [2 + 2 + 2] Cycloaddition of a,w-diynes with Nitriles
[Synthesis 2011, 2247-2254.] (special issue) See also the Correction: Errata (2011, 3928)
Picked up in ChemInform



Quick Access to Diverse Polymerizable Molecules (a Monomer Library) by Catalytic [2 + 2 + 2] Cycloaddition Reactions of Functionalized Alkynes
[ Macromolecules, 2010, 43, 2213-2218 ]


Synthesis of substituted anthracenes, pentaphenes and trinaphthylenes via alkyne cyclotrimerization reaction
[Tetrahedron Letters, 2010, 51, 1313-1316.]
Picked up in SYNFACTS(2010, p 423)



Selective Dimerization of 1,6-Diynes Catalyzed by Ionic Liquid-Supported Nickel Complexes in An Ionic Liquid/Toluene Biphasic System,
[Chem. Commun. 2009, 439-441.]
Picked up by SYNFACTS(2009, p 458 and ChemInform



Synthesis of Substituted 2,2'-Bipyridines and 2,2':6,2"-Terpyridines by Cobalt-Catalyzed Cycloaddition Reactions of Nitriles and a,w-Diynes with Exclusive Regioselectivity,
[Advanced Synthesis & Catalysis, 2008, 350, 143-152.]
Picked up in ChemInform



Efficient Activation of 2-Iminomethylpyridine/Cobalt-Baesd Alkyne [2 + 2 + 2] Cycloaddition Catalyst by Addition of a Silver Salt
[Advanced Synthesis & Catalysis, 2007, 349, 2368-2374]



On-Demand Generation of an Efficient Catalyst for Pyridine Formation from Unactivated Nitriles and -Diynes Using CoCl2-6H2O, dppe and Zn
[Organic Letters, 2007, 9, 931-934]



Iron-catalyzed intramolecular cyclotrimerization of triynes to annulated benzenes
[J. Organometallic Chemistry, 2006, 691, 3129-3136]
Picked up in ChemInform



A Highly Practical Instant Catalyst for Cyclotrimerization of Alkynes to Substituted Benzenes
[Organic Letters, 2006, 8, 1439-1442]
Picked up in ChemInform



Cobalt-catalyzed benzyl-alkynyl coupling
[Tetrahedron Letters, 2006, 47, 2591-2594]
Picked up in ChemInform



Intramolecular Cyclotrimerization of Triynes Catalyzedby N-Heterocyclic Carbene-CoCl2/Zn or -FeCl3/Zn
[Organic Letters, 2005, 7, 3065-3067]
Picked up in ChemInform



Cobalt-catalyzed mono-coupling of R3SiCH2MgCl with 1,2-dihalogenoethylene: A general route to gamma-substituted (E)-allylsilanes
[Tetrahedron Letters, 2004, 45, 4677-4679]
Picked up in ChmeInform

Copper-catalyzed intramolecular hydroamination of allenylamines to 3-pyrrolines or 2-alkenylpyrrolidnes
[Tetrahedonr Letters 2008, 49, 6529-6532]
Picked up in ChmeInform



Allylic Substitution Reactions with Grignard Reagents Catalyzed by Imidazolium and 4,5-Dihydroimidazolium Carbene-CuCl Complexes
[J. Organometallic Chemistry, 2005, 690, 6001-6007 and see also Erratum]
Picked up in ChmeInform



gamma-Selective allylic substitution reaction with Grignard reagents catalyzed by copper N-heterocyclic carbene complexes and its application to enantioselective synthesis
[Tetrahedron Letters, 2004, 45, 5585-5588]
Picked up in ChmeInform

Silica-supported silver as a green and sustainable catalyst for [3+2] cycloaddition reaction of azomethine ylides with 2’-hydroxychalcone derivatives
[ChemCatChem, 2018,　10,　2014-2018.]



Grignard allylic substitution reaction catalyzed by 1,2,3-triazol-5-ylidene magnesium complexes
[Tetrahedron Letters, 2013, 54, 1360-1363]



Grignard allylic substitution catalyzed by imidazol-2-ylidene- and imidazol-4-ylidene-magnesium complexes
[Tetrahedron Letters, 2010, 51, 5704-5707]



Carbonyl reduction with CaH2 and R3SiCl catalyzed by ZnCl2"
[Tetrahedron Letters, 2007, 47, 9120-9123.]
Picked up in ChemInform



Use of CaH2 as a reductive hydride source: Reduction of ketones and imines with CaH2/ZnX2 in the presence of a Lewis acid
[Tetrahedron Letters, 2005, 46, 1667-1669]
Picked up in Best Synthetic Methods: Reduction in Organic Chemistry Highlights. Picked up in ChemInform

Takeshi Yamada and Sentaro Okamoto,
"3,5,6-Trifluoro-2-pyridone effectively catalyses interrupted Passerini reaction of 3-(2- isocyanoethyl)-indole as a bifunctional catalyst. The described one-pot four-component coupling reaction enabled the rapid preparation of highly functionalised tetracyclic furoindolines",
Chem. Commun., 2022, 58, 11701-11704. [Link]open access


6-Halo-2-pyridone as an efficient organocatalyst for ester aminolysis
RSC Advances, 2021, 11, 24588-24593. [Link]open access



Simple and practical method for selective acylation of primary hydroxy group catalyzed by N-methyl-2-phenylimidazole (Ph-NMI) or 2-phenylimidazo[2,1-b]benzothiazoles (Ph-IBT)
[Tetrahedron Leetrs 2014, 55, 7039-7042.]


Structure–activity relationship of dihydroimidazo-, dihydropyrimido, tetrahydrodiazepino-[2,1-b]-thiazoles and -benzothiazoles as an acylation catalyst
[Tetrahedron Lett. 2014, 55, 1909-1912]



Synthesis and Catalytic Properties of 4-Aryl-2,3-dihydro-4H-pyrimido[2,3-b]benzothiazoles for Asymmetric Acyl or Carboxyl Group Transfer Reactions
[J. Org. Chem. 2011, 76, 6678-6685]
Picked up in ChemInform and Highlighted in Organic Chemistry Portal



Activity and behavior of imidazolium salts as a phase transfer catalyst for a liquid-liquid phase system
[Tetrahedron Letters, 2006, 47, 8055-8058]



Unexpected reactivity of annulated 3H-benzothiazol-2-ylideneamines as an acyl transfer catalyst
[Tetrahedron Letters, 2006, 47, 4347-4350]

Yuhsaku Okabe, Takeshi Yamada, and Sentaro Okamoto
"Nickel-Catalysed Cycloaddition Oligomerization of 1,6-Diynes to Medium-Size Cyclic Polyenes",
Polymer Chemistry, 2022, 13, 6075-6172. [Link]


Sentaro Okamoto, Yusuke Naito, and Ryosuke Nomura
”Synthesis of Folded H-Stacking Skipped p Polymers Consisting of Different 2-Substituted Trimethylene Tethering Units and Their Optical and Conductive Property",
Polymer, 2021, 230, 124037. [Link]

S. Okamoto, T. Yamada, T. Uchida, N. Kikuta, and Y. Kimura
"Dual-Mode Coupling Copolymerization of Aryl Dialdehyde and Alkynylaldehyde Monomers via Concurrent McMurry Olefination and Alkyne [2+2+2] Cycloaddition Trimerization Reactions Mediated by a Low-Valent Titanium Reagent",
Polymer, 2021, 214, 123344.
[Link]


Nana Kikuta, Takahiro Shindo, Yu-ki Sugiyama, Takeshi Yamada
and Sentaro Okamoto
Cobalt-Catalyzed [2 + 2 + 2] Cycloaddition Copolymerization of Diyne and Internal Alkyne Monomers to Highly Branched Polymers
Polymer, 2021, 212, 123133.[Link]


Synthesis and properties of folded π-stacking polymers having J-aggregative, alternative, and staggered assembling structures
Polymer, 2016, 97, 550-558.
[Link]




Catalytic [2 + 2 + 2] Cycloaddition Polymerization of Diyne–Nitrile Monomers in the Presence of CoCl2-6H2O/Diphosphine/Zn

J. Polym. Sci. A: Polym. Chem. 2016, 54, 345-351.

Design and synthesis of 2-(1,3-dialkoxy-2-methylpropan-2-yl)-1,3-diarylpropanes as tethering units for folded H-stacking polymers
Tetrahedron Letters, 2014, 55, 2649-2653.


Synthesis and Properties of Through-Space Conjugated Polymers Based on pi–pi Stacked 1,3-Biarylpropane Tethering Units
[J. Polymer Science Part A: Polymer Chemistry, 2013, 51, 3412-3419]



Synthesis of [—CH2C(CO2Et)2CH2Ar—]n Polymers and Their Unique Optical Properties by Through-Space Interactions between Ar and C=O Groups
[J.Polymer Science Part A: Polymer Chemistry, 2012, 50, 1707-1716]



Chain-Growth Cycloaddition Polymerization via a Catalytic Alkyne [2 + 2 + 2] Cyclotrimerization Reaction and Its Application to One-shot Spontaneous Block Copolymerization
[J. Am. Chem. Soc. 2011, 133, 9712-9715.]
Highlighted in ACS Noteworthy Chemistry and Selected as SYNFACT of the month



Folded H-Stacking Polymers by Conformational Control with 2-Substituted Trimethylene Tethers
[Macromolecules, 2010, 43, 6562-6569.]



Quick Access to Diverse Polymerizable Molecules (a Monomer Library) by Catalytic [2 + 2 + 2] Cycloaddition Reactions of Functionalized Alkynes
[ Macromolecules, 2010, 43, 2213-2218 ]

Takeshi Yamada and Sentaro Okamoto,
"3,5,6-Trifluoro-2-pyridone effectively catalyses interrupted Passerini reaction of 3-(2- isocyanoethyl)-indole as a bifunctional catalyst. The described one-pot four-component coupling reaction enabled the rapid preparation of highly functionalised tetracyclic furoindolines",
Chem. Commun., 2022, accepted. [Link]open access


Kouta Ibe, Haruki Nakada, Mayu Ohgami, Takeshi Yamada, and Sentaro Okamoto,
"Design, Synthesis, and Properties of des-D-Ring Interphenylene Derivatives of 1α,25-Dihydroxyvitamin D3",
Eur. J. Med. Chem., 2022, 243, 114795. [Link]


Takeshi Yamada, Kazuki Arai, Rie Kikuchi and Sentaro Okamoto
”Deuteration of Indole Compounds: Synthesis of Deuterated Auxins, Indole-3-acetic Acid-d5 and Indole-3-butyric Acid-d5", ACS Omega, 2021, 6, 19956-19963.
[Link]open access


Kouta Ibe, Takeshi, Yamada, Sentaro Okamoto,
"Synthesis and Vitamin D Receptor Affinity of 16-Oxa Vitamin D3 Analogues", Organic & Biomolecular Chemistry, 2019, 17, 10188-10200.
[Link]


Preparation of 2-hydroxy A-ring precursors for synthesis of vitamin D3 analogues from lyxose
[Tetrahedron Lett. 2015, 56 ,2315-2318.]


Generation of A Low-Valent Titanium from Titanatrane and Its Catalytic Reactions: Radical Ring Opening of Oxetanes
[Adv. Synth. Catal. 2013, 355, 2151-2157]



Stereoselective construction of 3a-methylhydrindanes starting from 2,7-enynol derivatives based on Ti(II)-mediated cyclization and Ru-catalyzed ring-closing metathesis
[Tetrahedron Letters, 2006, 47, 5181-5185]
Picked up in ChemInform



Formation of azatitanacyclopentanes from ene-imines and a Ti(O-i-Pr)4/2i-PrMgX reagent and their synthetic reactions
[Tetrahedron Lettrs, 2004, 45, 9037-9040]
Picked up in ChmeInform


Previously Synthesized Compounds