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Protodenitration, a direct reduction of nitroalkanes to corresponding alkanes, already spans two centuries and is enabled by various reagents. This mini‐review provides a historical development of the fundamental transformation and highlights the governing position of the Ono‐Tanner reaction employing tributyltin hydride. Due to the unchallenged dominance of the toxic tributyltin hydride and environmentally unpopular solvents sharply contrasting with modern ecological trends, the current situation was dubbed "the last fortress of tin's tyranny." [ABSTRACT FROM AUTHOR]

Keywords: nitroalkane; Ono-Tanner reaction; protodenitration; sustainable reduction; tributyltin hydride EN nitroalkane Ono-Tanner reaction protodenitration sustainable reduction tributyltin hydride 1 1 1 04/05/23 20230403 NES 230403 B The Front Cover b visually represents our review "The Last Fortress of Tin's Tyranny - Protodenitration of Nitroalkanes". Nitroalkane, Ono-Tanner reaction, protodenitration, sustainable reduction, tributyltin hydride Could the end of the last fortress of the tyranny of tin be in sight?" This review provides the historical development and highlights the governing position of the Ono-Tanner reaction employing tributyltin hydride. [Extracted from the article]

Anilines were protected as 2-(phenylseleno)ethanesulfonanilide (SeES anilide) via sulfonylation by 2-chlorosulfonyl chloride followed by the conjugate addition of benzeneselenol. The SeES anilide was deprotected by radical reduction using tributyltin hydride in the presence of AIBN. The corresponding anilines were obtained in high yields when the hydride and AIBN were added to the system slowly. Since the radical reaction proceeds under neutral conditions, chemoselective deprotection of the SeES group was accomplished. The SeES anilide was stable under various conditions, including some severe conditions. [ABSTRACT FROM AUTHOR]

Abstract: The catalytic hydrogenation of 4-methyl itaconate derivatives bearing a chiral auxiliary and their conjugate reduction with n-Bu3SnH in the presence of Lewis acid were examined to reveal their diastereoselectivity. The homogeneous catalytic hydrogenation of 4-methyl itaconyl (1S)-(−)-2,10-camphorsultam with the Crabtree''s catalyst [Ir(COD)(PCy3)(py)]PF6 in CH2Cl2–MeOH (2:1 v/v) gave less polar (1S,2′S)-diastereomer in 84% yield, while the conjugate reduction of the α-methylene amide with n-Bu3SnH (2 equiv) using MgI2 (7 equiv) as an additive in CH2Cl2 gave more polar (1S,2′R)-diastereomer in 70% yield. [Copyright &y& Elsevier]

This review describes the formation of five- and sixmembered heterocyces in various organic molecules by radical cyclization and covers the progress made on the topic during the period of 2008 through 2010. 1 Introduction 2 Reagents, Solvents, Radical Initiators, and Reactivity 3 General Mechanistic Pathways: Regio- and Stereoselectivity 4 Synthesis of Nitrogen Heterocycles 4.1 Nitrogen-Centered Radical Cyclizations 4.2 N-Vinylic and Related Systems 4.3 N-Allylic and Related Systems 4.4 N-Alkyl and Related Systems 4.5 Diastereoselective Radical Cyclizations 4.6 Cascade and Tandem Radical Cyclizations 4.7 Atom- and Group-Transfer Radical Cyclizations 4.8 Oxidative Radical Cyclizations 4.9 Miscellaneous 5 Synthesis of Oxygen Heterocycles 5.1 Diastereoselective Radical Cyclizations 5.2 Miscellaneous 6 Synthesis of Sulfur Heterocycles 7 Synthesis of Silicon Heterocycles 8 Miscellaneous 9 Conclusions [ABSTRACT FROM AUTHOR]

[image omitted] 2-Arylthio-β-C-D-glucopyranosides with a carbonyl or methoxy group in the lateral chain (1 and 2) can be converted to the corresponding 2-deoxy-β-C-D-glucopyranosides (1a and 2a) using Raney Ni. Reduction of 2-arylthio-β-C-D-glucopyranosides bearing an ester, methoxy, C≡N, or C=C moiety in the side chain (3-6) using n-Bu3SnH in the presence of azobisisobutyronitrile (AIBN) provided the corresponding 2-deoxy-β-C-D-glucopyranosides (3a-6a) without reducing additional functional groups. The application of n-Bu3SnH and AIBN in reaction with 2-arylthio-β-C-D-glucopyranoside (7) containing a Me3Si group bonded to the carbonyl fragment (7) resulted in the reduction of both the 2-ArS and C=O groups. [ABSTRACT FROM AUTHOR]

Abstract: A regioselective deuteration method for a wide variety of aromatic compounds using the halogen–deuterium exchange reaction initiated by Bu3SnH using THF-d 8 as the deuterium source was developed. [ABSTRACT FROM AUTHOR]

Synthesis of bicyclic carbocycles involving tributyltin hydride-mediated α-carbonyl radical cyclization reaction at room temperature has been reported. [ABSTRACT FROM AUTHOR]

Two hexoses and two pentoses have been reacted with two equivalents of trichloroacetaldehyde using boron trifluoride etherate as promoter in dioxane at reflux. The major products are exo-1,2- O -trichloroethylidenealdofuranoses in every case in varying yields, identical to the products previously obtained in lower yields using sulfuric acid or hydrochloric acid as promoter in trichloroacetaldehyde as solvent. Careful fractionation of the remainders of the product mixtures showed that the other isomer in the acetal ring was also produced in most cases but small amounts of the two 1,2- O -trichloroethylidenealdopyranose isomers were also produced. In addition, very small amounts of other products were identified that were derived from boron trifluoride etherate and the solvent. A mechanism involving rate-determining acetal ring closure was proposed to explain the formation of furanose derivatives, rather than pyranose derivatives. Methods for removal of the trichloroethylidene acetals were investigated for substituted derivatives and it was found that a process involving reduction with tributyltin hydride was effective. [Display omitted] • All monosaccharides react with chloral to give 1,2- O -trichloroethylideneglycofuranoses. • Two eq of chloral in dioxane with BF 3 as promoter gave better yields than chloral as solvent. • 1,2- O -trichloroethylideneglycopyranoses were obtained as minor products (0–5%). • Removal was done in good yield by reduction with tributyltin hydride then acetolysis. [ABSTRACT FROM AUTHOR]

The tin hydride-mediated cyclizations of a number of ethers, sulfides, and sulfones under mild, neutral conditions have been investigated. While the 2-bromobenzyloxy ethers were prepared in 62-65% yields by the alkylation of 4-hydroxy-1-phenyl-1,8-naphthyridin-2(1H)-one with 2-bromobenzyl bromides in refluxing acetone in the presence of anhydrous potassium carbonate, the sulfides were derived from 4-mercapto-1-phenyl-1,8-naphthyridin-2(1H)-one and 2-bromobenzyl bromides in 82-84% yields by a phase-transfer catalysis (PTC) reaction. The corresponding sulfones were prepared by treatment of the sulfides with m-CPBA in refluxing dichloromethane. The ethers, sulfides, and the sulfones were treated with nBu3SnH-AIBN to give regioselectively 1,8-naphthyridinone-annulated oxygen and sulfur heterocycles in 70-78% yields. [ABSTRACT FROM AUTHOR]

A method for the regioselective deuteration of pyrimidine and purine rings mediated by Bu3SnH using THF-d8 as a deuterium source on the basis of a radical reaction was developed. [ABSTRACT FROM AUTHOR]

Abstract: 2,4,6-Trichlorophenyl vinyl sulfonate smoothly undergoes intermolecular radical addition under mild initiation conditions mediated by tributyltin hydride and 1-ethylpiperidine hypophosphite (EPHP) to generate a range of functionalised alkyl sulfonamide precursors. This methodology can be used to prepare bifunctional pentafluorophenyl/2,4,6-trichlorophenyl sulfonates in good yields. [Copyright &y& Elsevier]

Abstract: We report herein that the conjugate reduction of α,β-unsaturated esters and amides, such as aryl acrylates, pantolactone esters of acrylic acids, diethyl itaconate and N-crotonylcamphorsultam, with tributyltin hydride proceeded in moderate to high yields in the presence of magnesium bromide diethyl etherate. The effect of metal halide enhancing the yields is also described. [Copyright &y& Elsevier]

Abstract: This review describes the formation of five- and six-membered heterocyclic rings in various organic molecules by radical cyclisation and covers mostly the literature published in 2005. [Copyright &y& Elsevier]

Abstract: We describe here a new synthesis of racemic α-amino acids containing polyfluorinated aliphatic long chain RF(CH2)3Y (RF =C2F5, C6F13, C8F17) (Y=CH(NH2)COOH) based on Sörensen''s method. The radical addition of perfluoroalkyl iodides RFI (RF =C2F5, C6F13, C8F17) at room temperature to ethyl-2-carbetoxy-2-phthalimido-pent-4-enoate 3 was first initiated by Et3B/O2. Then, the reduction of adducts 4a–c using Et3B/O2/Bu3SnH leads to ethyl-2-carbetoxy-2-phthalimido-5-perfluoroalkyl-pentanoate 5a–c under mild conditions. Experimental conditions for optimisation of the iodoperfluoroalkylation step using Et3B/O2 were studied. Finally, deprotection of 5a–c gave the desired products 6a–c in good yields. [Copyright &y& Elsevier]

The reactivity of the imidazol-5-yl in comparison to the imidazol-2-yl and phenyl radical under the reductive conditions of Bu3SnH, in intermolecular substitution reactions onto various aromatic substrates is reported. The directing effect of the hetero atom or methyl substituent in aromatic substrates was found to be more important than the polarity of the attacking σ-radical in determining the major product isomer. [Copyright &y& Elsevier]

Efficient 6-endo-trig free radical cyclisations of various 3-phenyl-acryl enamides to piperidin-2-ones, by using Bu3SnH and AIBN in boiling toluene, are reported. A different result has been observed for related enamide system without phenyl substituent at the 3-position of an acrylic moiety, as such a reaction of 3-methyl-butenoic acid cyclohex-1-enyl-methyl-amide afforded only the 5-exo-trig product. The difference in the cyclisation mode has been explained in terms of a reversible process leading to the thermodynamically more stable product. An application of this method for the tandem cyclisation permits to obtain idolizidine derivatives. [Copyright &y& Elsevier]

Chiral N-acylhydrazones derived from various aldehydes and N-amino-4-benzyl-2-oxazolidinone have previously been shown to be effective for acyclic stereocontrol of intermolecular radical and allylsilane additions. Treatment of the propionaldehyde hydrazone with tributyltin hydride in the presence of boron trifluoride etherate led to rapid chemoselective reduction of the imine bond in high yield. Preparation of similar hydrazones from ketones led to E/Z isomer mixtures, usually in ratios of 4:1 or greater. Geometry of the C&z.dbnd;N bond was assigned by steric compression shifts in 13C NMR spectra. Reduction with tributyltin hydride and boron trifluoride etherate afforded diastereomer mixtures in ratios very similar to the original E/Z isomer ratios. The chiral auxiliary blocked the opposite face of the C&z.dbnd;N bond relative to a related process using a chelated Lewis acid. A stereocontrol model involving monodentate interaction of the N-acylhydrazone and boron trifluoride is consistent with the observed stereochemical outcome. [Copyright &y& Elsevier]

Regioisomerically pure trifluoromethyl- and trifluoromethoxy-substituted aromatic and heteroaromatic aldehydes and carboxylic acids are valuable building blocks for the synthesis of biologically active molecules. They have been prepared by employing modern organometallic methods. On this basis, a novel access to 2,3-dihydro-5-(trifluoromethoxy)indole was developed which represents an intriguing example of how organometallic and radical chemistry can fecundate each other. [Copyright &y& Elsevier]

17-Formyl-androst-16-ene and its analogues were synthesized from the corresponding 17-iodo-16-ene derivatives in palladium-catalyzed formylation reaction using tributyltin hydride as hydrogen source under mild reaction conditions. The formation of androst-16-ene and its isomerization products, as well as that of analogous steroidal olefins as side-products, was found to be dependant on the reaction conditions. The formylation reaction tolerates various functional groups on the A and B rings of the steroids. [Copyright &y& Elsevier]

Abstract: Both (±)-protoemetinol, its 3-epi-isomer and (±)-3-desmethyl protoemetinol have been prepared in five linear steps from a dihydroisoquinoline using a 6-exo-trig cyclisation of a vinyl radical in the key step. This novel and particularly short route has potential application in the synthesis of Alangium and Mitragyna alkaloids. [Copyright &y& Elsevier]

Tributyltin hydride in N-methyl-2-pyrrolidinone (NMP) was used for the partial reduction of various functionalized acid chlorides at room temperature. This transition-metal-free procedure allows the synthesis of a range of (hetero)aromatic- and aliphatic aldehydes in good to excellent yields. [ABSTRACT FROM AUTHOR]

Abstract: Chlorodifluoromethyl ethers are easily obtained from the corresponding alcohols. These ethers, when treated with tributyltin hydride, produce difluoromethyl ethers in high yields. [Copyright &y& Elsevier]

Abstract: Tributyltin hydride-mediated straightforward synthesis of a new isoxazolo-benzazulene system from the derivatives afforded by the Baylis–Hillman reaction of 3-(2-bromophenyl)-4-isoxazolecarbaldehydes is described. [Copyright &y& Elsevier]

Abstract: Free radical-promoted one carbon ring expansion and chain extension of 1,3-diketones including 1,3-diarylpropane-1,3-diones and 2-aroyl-3,4-dihydro-2H-naphalen-1-one to generate corresponding 1,4-diketones are described. [Copyright &y& Elsevier]

Reaction of tributylstannyl, radical generated in situ with AIBN, with (2′,5′-di-O-tert-butyldimethylsilyl-3′-C-ethynyl-β-d-ribo-furanosyl)adenine (5) gave in 69% yield the new conformationally locked nucleosides 6 (E/Z). [Copyright &y& Elsevier]

The conjugate reduction of aryl acrylates performed with tributyltin hydride in the presence of magnesium bromide diethyl etherate in dichloromethane gave the corresponding saturated esters in moderate to high yields. The reduction of α-methylene-γ-benzyloxycarboxylic acid esters proceeded syn-selectively, but α-methylene-β-oxycarboxylic acid esters afforded reductive elimination products under the reaction conditions. [Copyright &y& Elsevier]

A novel synthetic protocol for the synthesis of [1,2-b]-fused bicyclic pyrazoles has been developed using radical cyclisation. The protocol uses cyclisation of pyrazole-1-(ω-alkyl) radicals generated from 1-[ω-(phenylselenyl)alkyl]-pyrazole precursors. The pyrazole natural product, withasomnine (3-phenyl-5,6-dihydro-4H-pyrrolo[1,2-b]pyrazole), and larger ring analogues have been synthesised in good yield using the protocol. A Bu3SnH-mediated oxidative cyclisation mechanism is facilitated by azo or Et3B radical initiators acting as oxidants of the intermediate π-radicals. [Copyright &y& Elsevier]