Total synthesis and structural confirmation of (±)-spirocollequins A and B
Keita Ichikawa, Toshiyasu Inuzuka, Hidemi Yoda and Tetsuya Sengoku
Tetrahedron Letters 2022, 107, 154109. (DOI: 10.1016/j.tetlet.2022.154109)

The first total synthesis of antiplasmodial isoindolinone alkaloids, spirocollequins A and B, has been accomplished. The proposed structures of spirocollequins have been supported through the comparison of spectroscopic properties of the synthetic samples with those of natural products as well as single-crystal X-ray diffraction analysis using a synthetic precursor of spirocollequin B.


Bifurcated synthesis of methylene-lactone- and methylene-lactam-fused spirolactams via electrophilic amide allylation of γ-phenylthio-functionalized γ-lactams
Tetsuya Sengoku, Koki Makino, Ayumi Iijima, Toshiyasu Inuzuka and Hidemi Yoda
Beilstein Journal of Organic Chemistry,  2020, 16, 2769–2775. (DOI: 10.3762/bjoc.16.227) 

New synthetic methods for spirolactams bearing an α-methylene-γ-butyrolactone or its analogous methylene-lactam have been developed.


Development of new catalytic enantioselective formation of methylenelactam-based N,O-spirocyclic compounds via ring opening-asymmetric reclosure of hydroxylactams
Tetsuya Sengoku, Ayako Miyoshi, Tamaki Tsuda, Toshiyasu Inuzuka, Masami Sakamoto, Masaki Takahashi and Hidemi Yoda
Tetrahedron,  2020, 76, 131252. (DOI: 10.1016/j.tet.2020.131252) 

Hydroxylactams prepared from N-carbonyl phthalimides and β-amido functionalized allylboronates underwent ring opening-asymmetric reclosure in the presence of catalytic amounts of MgBr2 and a chiral aminophenol to afford the corresponding N,O-spirocyclic compounds in excellent yields and high enantioselectivities.


Divergent synthesis of methylene lactone- and methylene lactam-based spiro compounds; Utility of amido-functionalized γ-hydroxylactam as a precursor for cytotoxic N,O– and N,N-spiro compounds
Tetsuya Sengoku, Anna Shirai, Ayaka Takano, Toshiyasu Inuzuka, Masami Sakamoto, Masaki Takahashi and Hidemi Yoda
The Journal of Organic Chemistry,  201984, 12532-12541. (DOI: 10.1021/acs.joc.9b02038)

Pharmaceutically attractive methylene lactone- and methylene lactam-based spiro compounds have been synthesized by employing amido-functionalized γ-hydroxylactam as a common intermediate.


New synthetic methodology toward azaspiro-γ-lactones via oxidative C-H spirocyclization reaction
Tetsuya Sengoku, Yuichiro Nagai, Toshiyasu Inuzuka and Hidemi Yoda
Synlett, 2019, 30, 199-202. (DOI: 10.1055/s-0037-1611941)

The key C–H spirolactonization was accomplished by employing iodobenzene diacetate and potassium bromide to afford a variety of azaspiro-γ-lactones in high yields. 

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