Synthesis of 4a-, 4e-phenyladamantanones and 2,4-o-benzenoadamantane by π-route

The acid catalysed reaction of 4-oxa-homoadamantan-5-one ($\text{1}$) with benzene yielded a mixture of 4^a-phenyladamantan-2-one ($\text{7}$), the equatorial isomer' ($\text{8}$) and 2-phenyl-2,4-o- benzenoadamantane ($\text{9}$) A plausible reaction pathway for the occurrence of $\text{9}$. is put forward. The structure of $\text{9}$, was deduced from spectroscopic data and reaction of the proposed intermediate 2,4^a-diphenyladamantan-2-ol ($\text{11}$) with acid. 2,4-o-Ben-zenoadamantane ($\text{16}$) is prepared likewise.     

Enantiocontrolled synthesis of (S)-3-substituted cycloalkanones from (s)-2-(p-tolylsulfinyl)-2-cycloalkenones and diorganomagnesium reagents.

By appropriate choice of reaction conditions, the $\text{same}$ enantiomerically pure ($\text{S}$)-(+)-2-($\text{p}$-tolylsulfinyl)cycloalkenone can be converted into $\text{either}$ an ($\text{R}$)-or an ($\text{S}$)-3-substituted cycloalkanone in good to excellent enantiomeric purity.     

N-methyl-N-anilinomethyl diphenylphosphine oxide: a versatile reagent for the synthesis of enamines

Cyclic as well as acyclic ketones, both saturated and α,β-unsaturated, can be converted into their homologous enamines by Horner-Wittig reaction with $\text{N}$-methyl-$\text{N}$-anilinomethyl diphenylphosphine oxide ($\text{3}$).     

On the mechanism of the formation of benzocyclobutene by flash vacuum pyrolysis of ortho-methylbenzyl chloride

Flash vacuum pyrolysis of $\text{o}$-methylbenzyl chloride-$\text{∝}$,$\text{∝}$-$\text{d}$₂ gives benzocyclobutene-$\text{∝}$,$\text{∝}$-$\text{d}$₂. This finding indicates that the reaction involves net δ-elimination of hydrochloric acid.     

The tert-butylation of nicotine: novel reaction pathways and racemization studies

The reaction of nicotine with $\text{tert}$-butyllithium gives 6-$\text{tert}$-butylnicotine ($\text{2}$) and two novel pyrrolidine ring cleaved products, $\text{3}$ and $\text{4}$; mechanisms for the racemization of $\text{1}$, $\text{2}$, and $\text{4}$ were elucidated by reacting $\text{tert}$-butyllithium with nicotine-2′-d₁.     

The facile (<−50°C) formation of cis-bicyclo[6.1.0]nona-2,4,6-trienes from cyclonona-1,3,5,7-tetraenes: A symmetry - forbidden reaction

The formation of the $\text{cis}$-bicyclo [6.1.0] nona-2,4,6-trienes $\text{4a}$-$\text{c}$ is not due to the sequence $\text{1}$ → $\text{2}$ → $\text{4}$, which would involve the symmetry-forbidden reaction $\text{2}$ → $\text{4}$ even at ?50°C. Rather, reaction of RX at C^4–7 of $\text{5}$, which is formed together with $\text{1}$, leads (probably via $\text{6a}$-$\text{c}$ and $\text{7a}$-$\text{c}$ to $\text{4a}$-$\text{c}$.     

N-Acylated α-aminonitriles and their conversion into 5-aminooxazole, 5(4h)-oxazolone and 4(5h)-imidazolone derivatives

In contrast with the reaction of α-aminonitriles $\text{1}$a, the corresponding $\text{N}$-acylated α-aminonitriles $\text{1}$b-f and oxalyl chloride do not yield pyrazinone derivatives, but 5-aminooxazoles $\text{9}$-$\text{11}$ or 4(5$\text{H}$)-imidazolones $\text{12}$, the latter being converted in some cases into imidazo [2,1-$\text{a}$]isoquinoline-2,5,6(3$\text{H}$)-triones. Reactions of compounds $\text{1}$b-f and ethyl chlorooxoacetate provide evidence for a 5(4$\text{H}$)-iminooxazole intermediate $\text{7}$, which aromatizes to yield 5-aminooxazoles $\text{9}$-$\text{11}$; however, unaromatizable īntermediates of type $\text{7}$ - isolable as 5(4$\text{H}$)y-oxazolones $\text{13}$ after hydrolysis - undergo a catalyzed Dimroth-type rearrangement to give imidazolone derivatives $\text{12}$.     

Acetylsanadaol,a diterpene having a novel skeleton,from the brown alga, Pachydictyon Coriaceum

Structures of new diterpenoids, sanadol ($\text{4}$) and acetylsanadol ($\text{5}$), isolated from $\text{Pachydictyon}$$\text{coriaceum}$, are determined, and sanadaol is produced by an acid-catalyzed ene reaction of dictyodial.     

A one-step transformation of aromatic aldehydes to nitriles,using S,S-Dimethylsulfurdiimide as iminating agent. Isolation of dithiatetrazocines as reaction intermediates.

$\text{S}$,$\text{S}$-Dimethylsulfurdiimide is explored as a novel and effective reagent for the direct synthesis of aromatic nitriles from aldehydes. A novel eight-membered heterocycle is isolated as a reaction intermediate and a mechanism for this reaction is discussed.     

On the novel reactivity of t-butyldimethylsilyl ether in prostaglandin synthesis: application to total synthesis of 11-epi-PGF2α

A facile 1,5-migration of a $\text{t}$-butyldimethylsilyl group and a new cleavage reaction of $\text{t}$-butyldimethylsilyl ether to alcohol in prostaglandin intermediates are described.     

Synthesis of trans-1,2-diphenyl-3,4-bis[4-(2,6-diphenyl-4H- pyranylidenyl)]cyclobutane: correction and structure proof

The reaction of phenyl lithium acetylide ($\text{2}$) with 2,6-diphenylpyrylium perchlorate ($\text{1}$) is solvent dependent. With diethyl ether as solvent, the isolated product differed from that previously reported and is reassingned as 2,6-diphenyl-4-phenylacetylenyl-4$\text{H}$-pyran ($\text{5}$). On the other hand, in THF the title compound ($\text{6}$) was obtained; its structure confirmed by single-crystal x-ray crystallography.     

Inept-29Si NMR study of a TiCl4-mediated reaction of an enol silyl ether

Condensation of 1,3-bis(trimethylsiloxy)-1-methoxybutadiene ($\text{1}$) and 2-phenyl-2,2-dimethoxyethanal ($\text{2}$) under TiCl₄ condition gave the γ-hydroxycyclopentenone product $\text{3}$. The reaction was followed by INEPT²⁹Si NMR. Implication to the mechanism of the reaction was discussed.     

Activation of methylenetriphenylphosphorane by reaction with t-butyl- or sec-butyllithium

Experimental details are provided to support a previous report that α-methylenetriphenylphosphorane ($\text{1}$) may be activated for reaction with unreactive substrates such as epoxides and hindered ketones by α-metallation to $\text{2}$.     

E- and Z-vinyloxyboranes (alkenyl borinates): stereoselective formation and aldol condensation

Vinyloxyboranes, intermediates of Hooz' reaction, are almost exclusively $\text{E}$-isomers which can be isomerized to the $\text{Z}$-isomers. Both isomers undergo stereoselective aldol condensations.     

Studies on structurally simple butenolides. VI. The polycyclic 3:1 adducts of protoanemonin with C-nucleophiles

X-Ray diffraction analysis yielded the constitution, configuration and conformation of a tetracyclic 3:1 adduct formed by reaction of protoanemonin $\text{1}$ with lithium dimethylcuprate. The same configuration was assigned by analogy to other tetracyclic 3:1 adducts formed by reaction of $\text{1}$ with lithium di-$\text{n}$-butylcuprate or di-methyl sodiomalonate. A pentacyclic 3:1 adduct also formed in the last reaction was fully assigned (constitution, configuration, conformation) by analysis of its 300 MHz 2-D COSY NMR spectrum.     

Reaction between N-acyl-2,3-dihydrobenzo-1,4-thiazine and N-acylphenothiazine with organometallic reagents

the title $\text{N}$-acyl-derivatives react with $\text{n}$-BuLi and Grignard reagents leading to products, which, formally, can be considered as derived from a Claisen-type condensation reaction.     

Asymmetric aldol reaction of amide enolates bearing trans-2,5-disubstituted pyrrolidines as chiral auxiliaries

Condensation of aldehydes with Zr enolate of chiral $\text{N}$-propionyl-$\text{trans}$-2,5-disubstituted pyrrolidine proceeded with high diastereo- and diastereoface-selection. Stereoselectivity in the reaction of the corresponding $\text{N}$-acetyl compounds was also examined.     

Decomposition of arilazides and p-tosylazide by thf/n-botyllithium. A new source of diazomethmne

Variously substituted arylazides, as well as $\text{p}$-tosylazide, when allowed to react at room temperature with THF previously treated with $\text{n}$-butyllithium, undergo a rapid decomposition affording the corresponding amines and fomamides, together with diazomethane. This diazo transfer (with deformylation) reaction is thought to involve the enolate of the acetaldehyde generated by the known cycloreversion of THF in the presence on $\text{n}$     

Preparation of fluoroalkylated benzoheterocycles using F-2-methylpropene

Several benzoheterocyclic compounds carrying a CH(CF₃)₂ group were prepared by the reactions of $\text{F}$-2-methylpropene with ortho-bifunctional benzenes. The reactivity and reaction mode of $\text{F}$-2-methylpropene in these reactions were compared with those of $\text{F}$-propene.     

Sodium 6-methoxy-(E,E)-3,5-hexadienoate: a useful diene in the aqueous diels-alder reaction

The sensitive dienol ether functionality in sodium 6-methoxy-($\text{E}$,$\text{E}$)-3,5-hexadienoate has been shown to be compatible with the conditions of the aqueous Diels-Alder reaction.