Diborane as a reducing agent - VI the novel reduction of indole-1-carboxaldehydes to 1-methyl- indoles,di(indolyimethyl) ethers and indolylmethyl indolines

Reduction of the indole-1-carboxaldehydes ($\text{1a}$-$\text{1f}$) with borane /THF gives the 1-methylindoles ($\text{4}$) in 42-91-% yields together with the di(indolylmethyl)ethers ($\text{8}$), the indolyl-methyl indolines ($\text{7}$), the unsymmetric ether($\text{10}$) and the indolenine ($\text{11}$) as the minor products, except $\text{7a}$. This appears to be the first report on the formation of symmetric ethers in the borane/THF reduction of an oxygen function. The formation of $\text{7a}$ and $\text{7b}$ from $\text{1a}$ and $\text{1b}$ implies that electrophilic substitution takes place primarily at position 3 of 3-substituted indoles, $\text{1c - 1f}$ did not form the corresponding $\text{7}$ probably because of steric hindrance. These results are discussed in relation to the mechanisms of borane/THF reduction, origin of the different products and electrophilic substitution in 3-substituted indoles.     

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 $\text{n}$     

Anomalies in the asymmetric hydroboration of olefins with the 11 adduct of (+)-α-pinene and BH3 · THF

The hydroboration of cis-2-butene and cis-3-hexene with pure diisopinocampheylborane (IPC₂BH) and monoisopinocampheylborane (IPCBH₂), both prepared from (+)-α-pinene, were studied. In contrast to IPC₂BH, which yielded R-(?)-2-butanol and R-(?)-3-hexanol in 98.4 and 94.5% optical purities, IPCBH₂ yielded S-(+)-2-butanol and S-(+)-3-hexanol in 23.6 and 19.7% optical purifies respectively. PMR examination of the methanolyzed products were utilized to establish the species present in the freshly prepared and aged $\text{1}\text{1}$ adduct from (+)-α-pinene and BH₃ · THF. The results confirm the interpretation previously advanced for the major differences realized in asymmetric hydroboration with the fresh and aged $\text{1}\text{1}$ adducts.     

Reactions and properties of some trimethyleneplatinum(IV) complexes: VII. Kinetics and mechanism of displacement of cyclopropane by alkenes

The kinetics of the reaction of alkenes (e.g. cis-pent-2-ene, hex-1-ene, cyclopentene) with [$\text{PtX}{}_2\text{(CH}{}_2\text{CH}{}_2\text{C}$H₂)(THF)₂] (X = Cl or Br, THF = tetrahydrofuran) or with [$\text{PtCl}{}_2\text{(CHPhCH}{}_2\text{C}$H₂)(THF)₂] in THF solution have been studied. The reactions occur with displacement of cyclopropane or phenylcyclopropane to give [PtCl₂(olefin)(THF)], and follow essentially second order kinetics, first order in both platinum complex and olefin. The mechanism of reaction is discussed.     

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.     

Studies on the stereochemical course of intramolecular cycloaddition reactions of olefinic o-quinodimethanes-stereoselective synthesis of 8α, 9α, 14β-estranes

The stereoselective synthesis of 3-O-methyl-7α-$\text{p}$-toluenesulphonyl-8α, 9α, 14β-estradiol ($\text{25}$) and its 11-oxo derivative ($\text{26}$) $\text{via}$ thermolysis of 1β-$\text{tert}$-butoxy-2α-[2-(4-methoxybenzocyclobutenyl)ethyl]-2β-methy1-3α-[2-($\text{p}$-toluenesulphonyl)ethenyl] cyclopentane ($\text{22}$) and its oxo derivative ($\text{24}$), which were derived from condensation product ($\text{9}$) of optically active aldehyde ($\text{8}$) and 1-cyano-4-methoxybenzocyclobutene through $\text{10}$ and $\text{11}$ to selenides $\text{16}$ and $\text{21}$, is described.     

Reduction d'acetals γ-bromo α-acetyleniques par les sels chromeux : Acces aux acetals et aldehydes α-alleniques.

Reduction of γ-bromo α-acetylenic acetals $\text{1}$ with chromous ions (THF + HMPA) in the presence of AcOH affords α-allenic acetals $\text{2}$ whose careful hydrolysis yields the corresponding aldehydes $\text{3}$. A new access to the dried bean beetle pheromone (racemic), via a Witting reaction with $\text{3a}$ is reported.     

C-Metallated reformatsky intermediates. Structure and reactivity.

¹³C-NMR analysis of the Reformatsky intermediates from t-b$\text{u}$tyl-α-bromo acetate, t-b$\text{u}$tyl-α-bromo isobutyrate and t-b$\text{u}$tyl-α-bromo pr$\text{o}$pionate have evidenced C-metallated species. Their ability to act as n$\text{u}$cleophilic reagents under mild conditions and their selectivity towards h$\text{a}$logen-and oxygen containing electrophiles is reported.     

A new steroidal lactone with plant growth-regulatory activity from dolichoslablab seed

A new plant growth-promoting sterol was isolated from immature seeds of $\text{Dolichos}$$\text{labla}$. The structure was elucidated as (22$\text{R}$, 23$\text{R}$-2α, 3α, 22, 23-tetrahydroxy-B-homo-7-oxa-5α-ergost-24(28)-en-6-one $\text{1}$.     

Isolation ofΔ9(11)-sterols from the sea cucumber psolusfabricii. Implications for holothurin biosynthesis

- 14α-Methyl-5α-cholest-9(11)-en-3β-ol ($\text{2}$) and 4α,14α-dimethyl-5α-cholest-9(11)-en-3β-ol ($\text{3}$) have been isolated from the sea cucumber $\text{Psolus}$$\text{fabricii}$ and characterised by ¹H NMR, ¹³C NMR and mass spectrometry. Lanost-9(11)-en-3β-ol ($\text{4}$) has also been tentatively identified. The relevance of this series of Δ⁹⁽¹¹⁾-sterols to holothurin biosynthesis is briefly discussed.     

Synthesis,structure, and reactions of thiocarbonic acid derivatives new pentathiodipercarbonates, (RSS)2 CS, α,α,α-tris(disulfides), and the first α,α,α-tris(trisulfide)

Novel bis(perhaloalkyl) pentathiodipercarbonates $\text{5b-d}$ have been synthesized by reaction of sulfenyl chlorides with metal trithiocarbonates, and the heptathio analog $\text{21a}$ was prepared similarly. Lenthionine $\text{19}$ is the main product when diiodomethane is treated with sodium tetrathiopercarbonate. A rearrangement of bis(alkyldithio)chloromethanesulfenyl chlorides $\text{22}$ to alkyldithio) (alkyltrithio)dichloromethanes $\text{24}$ has been observed. Additions of sulfenyl chlorides and of thiosulfenyl chlorides to the thiocarbonyl compounds $\text{5}$ and $\text{21a}$ were achieved in acetonitrile. The structures of the first crystalline pentathiodipercarbonate $\text{5a}$ and α,α,α-tris(disulfide) $\text{29a}$, and of the first reported α,α,α-tris(trisulfide)$\text{31a}$ have been determined by X-ray crystallography.     

Shinjulactone C,a new quassinoid ith a 1α, 12α:5α, 13α-dicyclo-9βH-picrasane skeleton from ailanthus altissima SWINGLE

A new non-bitter quassinoid, named shinjulactone C ($\text{1}$), was isolated from the root bark of $\text{Ailanthus altissima}$ SWINGLE and shown to be 1α, 12α:5α, 13α-dicyclo-1β, 12β, 20-trihydroxy-9β$\text{H}$-picras-3-ene-2, 11, 16-trione by X-ray diffraction method.     

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 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.     

Synthesis of 2β-fluoro-1α-hydroxyvitamin D3

2β-Fluoro-1α-hydroxyvitamin D₃($\text{3}$) was prepared from 1,2α-epoxy-cholest-5-en-3β-yl tetrahydropyranyl ether($\text{1a}$ via 2β-fluorocholest-5-ene-1α, 3β-diol($\text{2}$).     

Isolation of sterols with cyclopropyl-containing side chains from the cultured marine alga peridiniumfoliaceum

The sterol fraction of the cultured dinoflagellate $\text{Peridinium}$$\text{foliaceum}$ contains in addition to cholesterol, 24-methylcholesterol, 4,24-dimethylcholesterol and dinosterol ($\text{3c}$) small amounts of the cyclopropyl-containing sterols gorgosterol ($\text{1a}$) and 5α-gorgostanol ($\text{1b}$) as well as 4α-methylgorgostanol ($\text{1c}$) and E-4α,22ξ,23ξ (or 24ξ)-trimethylcholest-17(20)-en-3β-ol ($\text{6c}$ or $\text{7c}$). The biosynthetic implications of the first isolation of such sterols from a free-living alga are emphasized.     

A new class of isoquinoline alkaloids: The indenobenzazepines

The dark yellow indenobenzazepine alkaloids lahorine ($\text{1}$) and lahoramine ($\text{2}$) have been found in $\text{Fumaria}$$\text{parviflora}$ Lam. (Fumariaceae). In a transformation with biogenetic implications, treatment of the spirobenzylisoquinolines dihydrofumariline ($\text{4}$) and dihydroparfumidine ($\text{7}$) with methanesulfonyl chloride and triethylamine in dry THF, followed by iodine oxidation, provided $\text{1}$ and $\text{2}$, respectively.     

BH3 THF reduction of 3-methylisoxazolo [4,5-c]pyridines

3-Methylisoxazolo[4,5-c]pyridine $\text{1}$ on reduction with BH₃:THF gave, via the isolable complex $\text{4}$, the tetrahydroisoxazolopyridine $\text{5}$. The presence of two chlorine atoms at the 4 and 6 positions directed borane attact to the isoxazole ring, yielding the aminoethylpyridine $\text{8}$. Both types of reduction were obtained with 6-chloroisoxazolo[4,5-c]pyridine $\text{7}$.     

A novel synthesis of carbacyclin analogs via a stereoselective introduction of 15α-hydroxy group

(+/-)-6,9α-Methanoprostaglandin I₃, ($\text{2}$) and (+/-)-5,6-dihydro-6,9α-methano-6β-prostaglandin I₃, ($\text{4a}$) have been synthesized using a new method for the stereoselective introduction of the 15α-hydroxy group via a stereoselective electrophilic addition of phenyl-sulfenyl chloride to the enol ether ($\text{6}$) and ($\text{23}$) respectively.     

Ring cleavage rearrangement of cyclobutylmethylboranes

Boranes derived from hydroboration of methylenecyclobutane with borane/THF, 9-borabicyclo[3.3.1]nonane, and borane-methyl sulfide rearranged on heating in situ at 100–160°C to open chain structures. Products after oxidation were the unrearranged cyclobutylmethanol, and 4-penten-1-ol, 1,4-pentanediol and 1,5-pentanediol. The unsaturated alcohol was the major product in reactions with a stoichiometric ratio of alkene to BH bonds, and the diols were formed with excess borane. With borane-methyl sulfide as hydroborating reagent, the rate of rearrangement at 100°C in triglyme was not significantly dependent upon the initial alkene/borane ratio $\text{3}\text{1}$ or $\text{1.15}\text{1}$ or the presence of excess methyl sulfide. However, an equivalent amount of pyridine prevented rearrangement. Rearrangement in THF using borane/THF also occurred at comparable rates in the presence and absence of excess borane. Little or no isomerization of the boron function into the cyclobutane ring was observed. Results are interpreted on the basis of a concerted four-center mechanism which requires a vacant boron orbital.