1,2-dimagnesium derivatives of cyclopropane

cis-1,2-Dibromomagnesiocyclopropane (cis-$\text{4}$) was isolated from the reaction of both trans- and cis-1,2-dibromocyclopropane ($\text{1}$) with magnesium. The corresponding dialkylmagnesium species ($\text{7}$), an oligomer of 2-magnesabicyclobutane, was obtained from cis-$\text{4}$ by precipitation in THF; it forms a soluble complex 8 with HgBr₂.     

Synthesis of detoxininolactone derivatives and the revised absolute stereochemistry of detoxinine

A stereospecific synthesis of acetyl-$\text{L}$-valyl-detoxininolactone has been performed and the absolute stereochemistry of detoxinine has been revised to (2$\text{S}$, 3$\text{R}$, 1′$\text{S}$)-2-(2′-carboxy-1′-hydroxyethyl)-3-hydroxypyrrolidine.     

Cyanosugars III : The reaction of trimethylsilyl cyanide with keto,epoxy and acetal derivatives of carbohydrates

Reaction of methyl 2-acetamido-4,6-$\text{O}$-benzylidene-2-deoxy-α-$\text{D}$-$\text{ribo}$-hexopyranosid-3-ulose with Me₃SiCN afforded methyl 2-acetamido-4,6-$\text{O}$-benzylidene-3-$\text{C}$-cyano-2-deoxy-3-$\text{O}$-trimethylsilyl-α-$\text{D}$-$\text{allo}$- Reaction of ethyl 4,6-di-$\text{O}$-acetyl-2,3-anhydro-α-$\text{D}$-mannopyranoside with Me₃SiCN gave the corresponding ethyl 4,6-di-$\text{O}$-acetyl-2-$\text{C}$-cyano-2-deoxy-α-$\text{D}$-glucopyranoside. Reaction of methyl 4,6-$\text{O}$-benzylidene-2,3-anhydro-α-$\text{D}$-allopyranoside or methyl 4,6-$\text{O}$-benzylidene-2,3-di-$\text{O}$-tosyl-α-$\text{D}$-glucopyranoside with Me₃SiCN at - 75° or - 50° gave the corresponding methyl 6-$\text{O}$-[(R)-cyano phenyl methyl]-α-$\text{D}$-glyco-pyranosides with high or total regio and stereoselectivity.     

Addition products of hydrazine derivatives to azo-alkenes - III. α-phenylhydrazino-phenylhydrazones

The addition of phenylhydrazine to phenylazo-alkenes $\text{4}$ yields α-(1-phenylhydrazino)-phenylhydrazones $\text{1}$. The reaction of phenylhydrazine with α-halogenated carbonyl compounds $\text{5}$ affords either $\text{1}$ or the isomeric α-(2-phenylhydrazino)-phenylhydrazones $\text{2}$. Structures $\text{1}$ and $\text{2}$ (>N-NH₂ and-NH-NH- groups, respectively) can be differentiated by ¹H NMR in DMSO-D₆ solution. Possible pathways of the reactions leading to either $\text{1}$ or$\text{2}$ are discussed. Compounds $\text{1}$ are found to be precursors of phenylosazones $\text{6}$.     

Reactions of cyclo-octatetraene and its derivatives - X: 1,2,3,8-Tetraphenylcyclo-octatetraene and 2,3,4,5-tetraphenylcyclo-octa-1,3,5-triene

The reaction of tetracyclone $\text{1b}$ with the cyclo-octatetraene-dimethyl acetylenedicarboxylate adduct $\text{2}$ at $\text{ca}$. 110° produces, in addition to the $\text{exo}$[4+2] Π cycloadduct $\text{3b}$ (49%), 1,2,3,8-tetraphenylcyclo-octatraene $\text{5}$ (11%), together with the diketone $\text{11}$ (5%). In a similar reaction with the esterified cyclo-octatetraene-maleic anhydride adduct $\text{13a}$, the major product $\text{14}$ (82%) is accompanied by the cyclohexa-1,3-diene $\text{15}$ and the dihydrosemibullvalene derivative $\text{16}$. Thermolysis of $\text{3b}$ at $\text{ca}$. 145° leads to the cyclobutene $\text{12}$., which on catalytic hydrogonation followed by decarbonylation at 180°–190° gives 2,3,4,5-tetraphenylcyclo-octa-1,3,5-triene $\text{19}$. Attempted thermal conversion of $\text{19}$ into a dihydrosemibullvalene failed.     

1,2-Dialkoxycarbonylhydrazine derivatives of pyrroles and indolizines. A new synthesis of cycl[3.2.2]azines

The reaction of pyrroles $\text{1}$ with diisopropyl azodicarboxylate $\text{2}$ yields 2- and 2,5-substituted derivatives. 3- and 1,3-substituted indolizines $\text{5}$ and $\text{6}$ are formed by the same route. Cycl[3.2.2]azines $\text{7}$ have been obtained from $\text{5}$ and $\text{6}$ with dimethyl acetylenedicarboxylate.     

Photo-oxygenations of 1H-azepine derivatives isolation and characterization of the [6+2] cycloaddition product

The reactions of 1H-azepine derivatives ($\text{1a-b}$ and $\text{4}$) with singlet oxygen gave the [6+2] cycloadducts ($\text{2a-b}$) and the [4+2] cycloadducts ($\text{3a-b}$ and $\text{5}$). The thermal and base-catalyzed rearrangements of the oxygen-adducts were investigated.     

Synthesis of oxapenem derivatives by novel reductive cyclization

Several 6-ethyl-substituted l-oxapenem derivatives were synthesized by the application of the established method. Furthermore novel and effective synthesis of oxapenems $\text{via}$ reductive cyclization of 2-chloro-2-(4-chloro-3-ethyl-2-oxo-l-azetidinyl) acetoacetates ($\text{1}$$\text{0}$) using sodium thiolates is reported.     

New facile synthesis of N-sulfinylamine derivatives using N,N′-sulfinylbisimidazole and N-(chlorosulfinyl)imidazole

Treatment of amine derivatives such as amines, sulfonamides, and amides with N,N′-sulfinylbisimidazole $\text{1}$ and N-(chlorosulfinyl)imidazole $\text{2}$$\text{in situ}$ respectively gives the corresponding N-sulfinylamine derivatives ($\text{3}$); the latter reaction using N-(chlorosulfinyl)imidazole $\text{2}$ yields $\text{3}$ in almost quantitative yields at 20°C under mild conditions.     

A novel synthesis of 3-cyanoindoles and a new route to indole-3-carboxylic acid derivatives

2-Alkyl-3-cyanoindoles are obtained when 1-alkylmethyl-2-chloro-(or 2-phenylsulfonyl)-3-phenylsulfonylindoles are reacted with excess azide ion (90°/DMF). The reaction is considered to occur by a fragmentation recombination process in which the Schiff's base $\text{12}$ is of central importance. This proposal is supported by the formation of 2-substituted indole-3-carboxylates $\text{17}$ from aldehydes and the α-phenylsulfonyl-$\text{o}$-aminophenylacetic acid ester derivative $\text{16}$.     

Trifluoroacetoxy-phenylselenation of nitroolefins regioselective preparation of nitroallylic alcohol derivatives and their use as multiple coupling reagents

It has been shown In previous papers that the pivalate of 2-nitro-2-propen-1-ol (NPP, $\text{1}$), a nitroolefin with allylic leaving group, can be used as a versatile multiple coupling reagent. The present contribution describes the preparation of NPP analogues, substituted in the 1- and/or 3-position of the allylic carbon skeleton. Standard methods of nitroaliphatic chemistry readily provide symmetrically substituted derivatives such as the cyclohexenes ($\text{7}$) and the indenes ($\text{8}$), while unsymmetrical ones such as the phenyl NPP $\text{9}$ are not so easy to prepare. This situation is now greatly improved by a regioselective method of introducing an allylic pivaloyloxy group into nitroolefins: in the first step of the four-step sequence a phenylseleno- and a trifluoroacetoxy-group are added across the nitroolefinic double bond ($\text{10}$ → $\text{11}$), then, the trifluoroacetate is cleaved, and tne resulting nitro-phenylseleno-alcohol $\text{12}$ is oxidized with elimination to the nitroallylic alcohols $\text{13}$. These are pivalated by pivalic anhydride/ BF₃· etherate (→ $\text{14}$). - The regioselective preparation of the products $\text{16}$–$\text{34}$ of nitroallylation of various nucleophiles with substituted NPP-type reagents demonstrates the broad scope of these multiple coupling reagents. Due to the multitude of conversions of the nitro group, these reagents provide access to a great variety of structures without NO₂ -substituents, cf. $\text{2}$ and $\text{3}$. The mechanism of the reaction of NPP-derivatives is discussed.     

Anionic tricarbonyl derivatives of molybdenum and tungsten and their reactions with allyl halides

A series of carbonylmetallate anions $\text{fac}$-[MX(CO)₃L₂]^?, where M = Mo or W, X = Cl, Br or I and L₂ = 1,10-phenanthroline(phen) or 2,2′-bipyridine(bipy) have been prepared from the corresponding $\text{cis}$-M(CO)₄L₂ complexes. No evidence of $\text{fac}$-to $\text{mer}$-isomerisation was evident on dissolution, although in MeCN solvolysis occurred with the formation of $\text{fac}$-M(CO)₃L₂(MeCN). Reaction of the anions with various allyl halides resulted in high yields of η³-allyl complexes [MX(CO)₂(η³-RC₃H₄)L₂]. The significance of these observations for the mechanism of the allyl oxidative-addition reaction are discussed.     

Action of tert-butyl azidoformate on the conjugate bases of 1,2,3,4-tetrahydro-9H-carbazole and other indole derivatives

tert-Butyl azidoformate ($\text{2}$) reacts with the conjugate bases of $\text{3a}$, $\text{7a}$, $\text{9}$ (R¹ = R² = CH₃), and $\text{9}$ (R¹ = CH₃, R² = H) to give products [$\text{4}$, $\text{8}$, $\text{12}$, and $\text{14}$, respectively] in addition to the expected N-(tert-butoxycarbonyl)indole derivatives.     

Synthesis and conformational behaviour of 1,9,17-triaza[2.2.2]metacyclophane-2, 10, 18-trione derivatives

The 1,9,17-triaza[2.2.2]metacyclophane-2, 10, 18-trione derivatives ($\text{1}$) – ($\text{3}$) have been synthesised. X-Ray crystallography shows that the 1,9,17-trimethyl derivative ($\text{3}$) adopts a Crown conformation ($\text{11}$) in the solid state. Dynamic n.m.r. spectroscopy indicates that both the 1,9-dimethyl-17-benzyl- ($\text{2}$) and 1,9,17-trimethyl- ($\text{3}$) derivatives exist as interconverting mixtures of Crown ($\text{11}$) and Saddle ($\text{12}$) conformations with the former predominating at equilibrium in solution.     

Cycloaddition reactions of 1,3-benzothiazines - 6. Reactions of 1,3-benzothiazine derivatives with substituted acetyl chlorides

6, 7-Dimethoxy-2$\text{H}$-l,3-benzothiazine derivatives ($\text{1}$, $\text{8}$) react with substituted acetyl chlorides to give angularly condensed β -lactams ($\text{3a}$-$\text{d}$, $\text{10}$, $\text{11}$). The $\text{cis}$ compound $\text{11}$ was epimerised to the $\text{trans}$ derivative $\text{12}$. From the interaction of 2-phenyl-6,7-dimethoxy-4$\text{H}$-1,3-benzothiazine ($\text{7}$) and α -chloro-phenylacetyl chloride two stereoisomeric β -lactam derivatives ($\text{9a}$, $\text{b}$) were isolated, whereas in the other cases studied the reactions leading to β -lactams proved to be stereospecific. Analogous reactions of $\text{4}$-methyl-6,7-dimethoxy-2$\text{H}$-l,3-benzothiazine ($\text{5}$) furnished the enamides $\text{6a}$,$\text{c}$, $\text{d}$. Structures of the new compounds and configurations of the diastereomers were elucidated by IR and NMR spectroscopy.     

Efficient syntheses of naturally occurring 3,4-dihydroxyprolines: Electrophile-mediated lactonization of 2-amino-3-hydroxy-4-pentenoic acid derivatives

Stereospecific conversion of β-hydroxyallylglycine derivatives into (2$\text{S}$, 3$\text{R}$, 4$\text{R}$) 1 and (2$\text{S}$, 3$\text{S}$, 4$\text{S}$) 2 $\text{via}$ halo- or mercuri-lactonization has been described.     

Proton and carbon nuclear magnetic resonance study on some n- and o-acyl derivatives of monohydroxypyridines

Comparative study on the proton and carbon NMR spectra for a series of $\text{N}$- and $\text{O}$-acyl substituted monohydroxypyridines (C₅H₄NO$\text{R}$: $\text{R}$=-H, -CHO, -COCH₃, -COC(CH₃)₃, -COCF₃, -COC₆H₅, -SO₂CH₃, -SO₂C₆H₄CH₃ is reported. p]Characteristic ¹H, ¹³ NMR and IR spectral features allow simple and unambiguous distinction between the isomeric $\text{N}$- and/or $\text{O}$-acyl-derivatives of 2-, 3- and 4-hydroxypyridines, so that both forms can clearly be identified when tautomeric equilibria occur, since the tautomerism rate is slow on the NMR time scale     

Syntheses of trifluoromethylated diene derivatives through the claisen rearrangement of trifluoromethylated propargylic and allylic alcohols

3-Trifluoromethyl-2Z, 4E-dienoate ($\text{14}$) and the dienamide ($\text{10}$,$\text{11}$) were prepared through the Claisen rearrangement of trifluoromethylated propargylic and allylic alcohols.     

CC bond formation from schiff base and vinyloxyborane: Synthesis of β-amino acid derivatives

An efficient methodology for the preparation of β-amino acid derivatives ($\text{3}$) by CC bond formation from Schiff bases ($\text{1}$) and vinyloxyborane ($\text{2}$) and their utilization in the synthesis of the pyrimidine moiety ($\text{3f}$) of bleomycin are described.     

Fluorine-containing amino acids and their derivatives. 6. An efficient synthesis of β-fluorinated alanines via fluorohalomethylation of aminomalonates

Aminomalonates, e.g., $\text{1}$ and $\text{2}$, smoothly reacted with difluoro- and chlorofluorocarbene to produce the adducts ($\text{3}$, $\text{4}$, and $\text{5}$) in good yields. These products were successfully converted to various versatile β-fluorinated alanine derivatives, i.e., β,β-difluoroalanine ($\text{6}$), N-acyl-β-fluorodehydroalaninate ($\text{7}$), and fluoropyruvic acid ($\text{8}$).