Nagatoshi Nishiwaki

Catalytic Enantioselective Addition of Nitro Compounds to Imines—A Simple Approach for the Synthesis of Optically Active β-Nitro-α-Amino Esters†

The catalytic and asymmetric nitro-Mannich reaction of nitro compounds to α-imino esters catalyzed by chiral bisoxazoline-copper complexes [Eq. (1); Pg = protecting group] gave β-nitro-α-amino esters with excellent diastereo- and enantioselectivities. The reactions can be performed under ambient conditions.

Methods and applications of cycloaddition reactions in organic syntheses

PREFACE ix CONTRIBUTORS xi PART I [2+1] CYCLOADDITION 1 [2+1]-TYPE CYCLOPROPANATION REACTIONS 1 Akio Kamimura 2 N1 UNIT TRANSFER REACTION TO C--C DOUBLE BONDS 67 Satoshi Minakata, Youhei Takeda, and Kensuke Kiyokawa PART II [2+2] CYCLOADDITION 3 LEWIS BASE CATALYZED ASYMMETRIC FORMAL [2p2] CYCLOADDITIONS 89 Andrew D. Smith, James Douglas, Louis C. Morrill, and Edward Richmond PART III [2+2] AND [4+2]/[2+2] CYCLOADDITION 4 CATALYTIC [2p2] CYCLOADDITION OF SILYL ENOL ETHERS 115 Yosuke Yamaoka and Kiyosei Takasu PART IV [3+2] CYCLOADDITION 5 [3p2] CYCLOADDITION OF a,b-UNSATURATED METAL CARBENE COMPLEXES 135 Ryukichi Takagi and Manabu Abe 6 GEOMETRY-CONTROLLED CYCLOADDITION OF C-ALKOXYCARBONYL NITRONES: SYNTHETIC STUDIES ON NONPROTEINOGENIC AMINO ACIDS 151 Osamu Tamura 7 RECENT ADVANCES IN CATALYTIC ASYMMETRIC 1,3-DIPOLAR CYCLOADDITIONS OF AZOMETHINE IMINES, NITRILE OXIDES, DIAZOALKANES, AND CARBONYL YLIDES 175 Hiroyuki Suga and Kennosuke Itoh 8 CONDENSATION OF PRIMARY NITRO COMPOUNDS TO ISOXAZOLE DERIVATIVES: STOICHIOMETRIC TO CATALYTIC 205 Francesco De Sarlo and Fabrizio Machetti 9 CARBAMOYLNITRILE OXIDE AND INVERSE ELECTRON-DEMAND 1,3-DIPOLAR CYCLOADDITION 223 Nagatoshi Nishiwaki and Haruyasu Asahara PART V [3+2], [3+3], AND [4+2] CYCLOADDITION 10 CYCLOADDITION REACTIONS OF SMALL RINGS 241 Steven D. R. Christie and Hayley T. A. Watson PART VI [3+2] AND [5+1] CYCLOADDITION 11 DEVELOPMENT OF NEW METHODS FOR THE CONSTRUCTION OF HETEROCYCLES BASED ON CYCLOADDITION REACTION OF 1,3-DIPOLES 263 Yutaka Ukaji and Takahiro Soeta PART VII [3+3] CYCLOADDITION 12 A FORMAL [3p3] CYCLOADDITION APPROACH TO NATURAL PRODUCT SYNTHESIS 283 Jun Deng, Xiao-Na Wang, and Richard P. Hsung PART VIII [4+2] CYCLOADDITION 13 [4p2] CYCLOADDITION CHEMISTRY OF SUBSTITUTED FURANS 355 Scott Bur and Albert Padwa 14 SYNTHESIS OF SUBSTITUTED OLIGOACENES VIA DIELS ALDER REACTIONS AND SUBSTITUENT EFFECTS ON MOLECULAR STRUCTURE, PACKING ARRANGEMENT, AND SOLID-STATE OPTICAL PROPERTIES 407 Chitoshi Kitamura 15 CYCLOREVERSION APPROACH FOR PREPARATION OF LARGE p-CONJUGATED COMPOUNDS 429 Hidemitsu Uno PART IX [4+2]/[3+2] CYCLOADDITION 16 TANDEM [4p2]/[3p2] CYCLOADDITIONS 471 Ramil Y. Baiazitov and Scott E. Denmark PART X [5+1] CYCLOADDITION 17 TRANSITION METAL-CATALYZED OR -MEDIATED [5p1] CYCLOADDITIONS 551 Xu-Fei Fu and Zhi-Xiang Yu PART XI [4+3] CYCLOADDITION 18 [4p3] CYCLOADDITIONS OF ENOLSILANE DERIVATIVES 565 Sarah Y. Y. Lam and Pauline Chiu 19 APPLICATION OF THE [4p3] CYCLOADDITION REACTION TO THE SYNTHESIS OF NATURAL PRODUCTS 599 Darin E. Jones and Michael Harmata PART XII [5+2] CYCLOADDITION 20 RECENT DEVELOPMENTS IN THE [5p2] CYCLOADDITION 631 Herve Clavier and Helene Pellissier INDEX 655

Metal-Free α‑Hydroxylation of α‑Unsubstituted β‑Oxoesters and β‑Oxoamides

A direct metal-free α-hydroxylation of α-unsubstituted β-oxoesters and β-oxoamides was developed using m-chloroperbenzoic acid as the oxidant. This transformation enabled straightforward metal-free access to important α-hydroxy-β-dicarbonyl moieties under mild reaction conditions. Furthermore, the hydroxylated products were readily converted into vicinal tricarbonyl compounds, which are useful synthetic precursors of numerous biological targets.

Novel functionalization of 1-methyl-2-quinolone; dimerization and denitration of trinitroquinolone

New methods for functionalization of 1-methyl-2-quinolone (MeQone) skeleton are provided. The reaction of 1-methyl-3,6,8-trinitro-2-quinolone (TNQ) with amines affords quinolone dimer 1 and 6,8-dinitroquinolone (6,8-DNQ). Dimerization predominantly proceeds at room temperature, and denitration takes place under heated and diluted conditions. We also provide a plausible mechanism for these reactions on the basis of structure–reactivity relationship of amines.

Improved generation method for functionalized nitrile oxide

Abstract Gentle generation of nitrile oxide bearing a carbamoyl group was performed. 4-Nitro-3-isoxazolin-5-one was treated with dipolarophiles in the mixed solvent ( MeCN H 2 O ) at room temperature to afford cycloadducts in good yields.

A novel nitrile oxide precursor ; 2-methyl-4-nitro-5(2H)-isoxazolone

2-Methyl-4-nitro-5(2H)-isoxazolone (1) was found to be a versatile precursor for a functionalized nitrile oxide by reaction with dipolarophiles giving 3-(N-methylcarbamoyl) isoxazole (2 or 3) derivatives

An anomalous hydration/dehydration sequence for the mild generation of a nitrile oxide

A nitrile oxide containing a carbamoyl group is readily generated upon the treatment of 2-methyl-4-nitro-3-isoxazolin-5(2H)-one with water under mild reaction conditions, even in the absence of special reagents. The obtained nitrile oxide undergoes cycloaddition with dipolarophiles, alkynes and alkenes, to afford the corresponding isoxazol(in)es, which are useful intermediates in the synthesis of polyfunctionalized compounds. A plausible mechanism underlying the formation of the nitrile oxide is proposed, which involves an anomalous hydration/dehydration sequence. DFT calculations were also performed to support this mechanism.

Synthesis of 4‑Substituted 3,5-Dinitro-1,4-dihydropyridines by the Self-Condensation of β‑Formyl-β-nitroenamine

3,5-Dinitro-1,4-dihydropyridines (DNDHPs) are readily constructed by the acid-promoted self-condensation of β-formyl-β-nitroenamines. In the DNDHPs, one molecule of the nitroenamine serves as a C3N1 building block and the other serves as a C2 block. This synthetic method does not require any special reagents and conditions. When the reaction is conducted in the presence of electron-rich benzene derivatives, arylation at the 4-position of DNDHP is achieved by trapping the 3,5-dinitropyridinium ion intermediate.

Chemistry of Nitroquinolones and Synthetic Application to Unnatural 1-Methyl-2-quinolone Derivatives

The 1-methyl-2-quinolone (MeQone) framework is often found in alkaloids and recently attention was drawn to unnatural MeQone derivatives with the aim of finding new biologically active compounds, however, low reactivity of the MeQone framework prevents the syntheses of versatile derivatives. A nitro group is one of the useful activating groups for this framework that enables a concise chemical transformation. Among nitroquinolones, 1-methyl-3,6,8-trinitro-2-quinolone (TNQ) exhibits unusual reactivity favoring region-selective cine-substitutions that afford 4-substituted 1-methyl-6,8-dinitro-2-quinolones upon treatment with nucleophilic reagents. Contrary to this, 1-methyl-3,6-dinitro-2-quinolone (3,6-DNQ) does not undergo any reaction under the same conditions. The unusual reactivity of TNQ is caused by steric repulsion between the methyl group at the 1-position and the nitro group at the 8-position, which distorts the MeQone framework. As a result, the pyridone ring of TNQ loses aromaticity and acts rather as an activated nitroalkene. Indeed, the pyridone moiety of TNQ undergoes cycloaddition with electron-rich alkenes or dienes under mild conditions, whereby a new fused ring is constructed on the [c]-face of the MeQone. Consequently, TNQ can be used as a new scaffold leading to versatile unnatural MeQone derivatives.

Green Chemical Catalyst Supported on S-Terminated GaN(0001)

A novel function of nitride-based semiconductor is successfully developed for organic synthesis, in which palladium supported on the surface of sulfur-terminated GaN(0001) serves as a unique green chemical catalyst. It efficiently catalyzes Heck reaction with simple manipulations and its catalytic activity is retained for several repeat reactions. Moreover, it is easily reused without any special treatment. A plausible mechanism for Pd adsorption is provided for the first time; the –SH groups on the surface of the substrate attract Pd2+, and reduce to Pd0. The presence of Pd0 on the surface was confirmed by X-ray photoelectron spectroscopy measurements.