The formation and subsequent cyclisation of novel hydroperoxides from a 1,4− and a 1,5-diene

The preparation of the unsaturated hydroperoxides ($\text{3}$,$\text{4}$,$\text{5}$,$\text{6}$ and $\text{7}$) by the sensitized photooxidation of the 1,4-diene($\text{1}$) and the 1,5-diene($\text{2}$) is described, together with the attempted free-radical cyclisation of these.     

Phosphorus heterocycle synthesis by RPX2,· AlX3 addition to [1,n]dienes VII.

The RPX₂·AlX₃ complex ($\text{1}$) reacts with unsaturated ketones and imines to give novel 7-oxa and 7-aza-2-phosphabicyclo[2.2.1]heptanes (compounds $\text{3}$ and $\text{6}$ respectively).A new 1,3-dipolar addition of (CH₃)₂ CCH₂P?XR to nArN=C=S was disclosed resulting in the formation of the 2-imino-1,3-thiaphospholanes ($\text{7}$).     

A novel route to aldehydic enol ethers and enamines

Base-promoted reaction of dimethyl diazomethylphosphonate ($\text{1}$) with dialkyl and cyclic ketones in the presence of alcohols and of amines affords aldehydic enol ethers and enamines, respectively.     

Conversion of the allylic and homoallylic steroidal alcohols to the corresponding saturated ketones by means of the activated Ra/Ni

Conversion of the allylic and homoallylic alcohols ($\text{1}$) and ($\text{2}$) to the corresponding saturated ketones ($\text{3}$) and ($\text{4}$), by means of the activated Ra/Ni, in the presence of cyclohexanone, was achieved stereospecifically and high yields.     

Functionalisation of unactivated methyl groups through cyclopalladation reactions

The transformation of the organopalladium compound (3) into the corresponding deuteriated, chlorinated, or oxidized derivatives (7), (8), or (9), (11), and (12) respectively. is described. The palladation of compound (9) takes place regioselectively leading to the palladated system (13), which is transformed into the difunctionalised oximes (15) and (16). The palladation of $\text{E}$-2,2-dimethyl and 2,2,6,6-tetramethyl-cyclohexanone oxime leads to the corresponding organopalladium compounds (17) and (27), which through deuteriation or oxidation affords the expected products (21) and (31), or (22), (23), (24), and (32), respectively. The second palladation of the compound (22) takes place on the remaining methyl group yielding the organopalladium derivative (26). Finally, $\text{E}$-lupanone oxime is palladated selectively in the 23-position leading to the organopalladium compound (38); the transformation of this compound into its 23-deuterio and 23-acetoxy- derivatives (41) and (42), respectively is also described. The stereochemistry in the palladatlon of lupanone oxime is deduced from NOE studies at 500 MHz.     

γ-Lactam analogues of penicillanic and carbapenicillanic acids

Synthesis and biological activity of γ-lactam analogues of penicillanic and carboapenicillanic acids, and the sodium periodate mediated rearrangement of pyrrolidine-2,3-diones are described. 1,3- Dipolar addition of cyclic nitrone (6) and methyl acrylate afforded the bicyclic adducts (7a) and (7b). Reductive cleavage of the N-O bond and subsequent cyclisation of a regioisomer (11a) gave the γ-lactams (12a) and (12b) in a ratio of 85 : 15. They are transformed to the carbapenam analogues (1)-(4). Their stereochemistry was assigned according to the X-ray structure of the γ-lactam (12b). Benzyl 6-oxopenicillanate (20) was directly transformed to the γ-lactam analogue (5) $\text{via}$ a novel ring expansion. These synthetic analogues did not show antibiotic activity or β-lactamase inhibition. Treatment of pyrro1idine-2,3-diones (25a) and (25b) with sodium periodate gave ring contracted β-lactams (26a) and (26b) respectively. Similar treatment of (27) followed by diazomethane afforded an unexpected spiro epoxide.     

Keto-alkyne cyclisation reactions: heterocyclic prostacyclin analogues

Simple furan, thiophene and pyrrole analogues of prostacyclin have been prepared from readily-available 4-alkvnyl ketones; the cyclohexa[b]-furano-prostacyclin analogue $\text{3}$ has also been synthesised using the keto-alkyne cyclisation procedure.     

Chemistry of 1,4-dioxene II : A new method for the two-carbon homologation of aldehydes and ketones to α-hydroxymethyl ketones

1,4-Dioxen-2-yl lithium $\text{2}$ reacts with ketones or aldehydes to give alcohols $\text{3}$ which lead after an allylic rearrangement under mild conditions, followed by reduction and hydrolysis to α-hydroxymethyl ketones in fair yields.     

Studies on the reduction of cyclic 1,3-diketones via their triflates

Using 1,3-Cyclohexadione ($\text{1}$) and 5,5-dimethyl-1,3-Cyclohexadione ($\text{11}$) as examples, it is shown that 1,3-diketones can be transformed into monoketones, monoalcohols, alkanes and unsaturated ketones.     

A novel synthesis of allyl vinyl ethers

Base-promoted reaction of dimethyl diazomethylphosphonate ($\text{2}$) with aliphatic ketones in the presence of allylic alcohols affords aldehydic allyl vinyl ethers ($\text{3}$).     

Dehalogenation of α -haloketones and vic-dibromides with nickel boride

α-Haloketones and $\text{vic}$-dibromides are converted to the corresponding ketones and alkenes respectively with nickel boride generated $\text{in situ}$ from sodium borohydride and nickel chloride.     

Synthesis of erythrinin A,a naturally occurring pyranoisoflavone

Erythrinin A ($\text{10}$) has been synthesised by the oxidative rearrangement of dihydropyranochalcone $\text{1}$ with thallium(III) nitrate (TTN) in trimethyl orthoformate (TMOF) to the dimethyl acetal $\text{2}$, followed by cyclisation to $\text{3}$, demethylation to $\text{6}$ and dehydrogenation. Compound $\text{10}$ could also be obtained from chalcone $\text{4}$ on similar rearrangement followed by cyclisation, demethoxymethylation and dehydrogenation. In another route, chalcone $\text{7}$ was oxidatively rearranged with TTN in TMOF, to $\text{8}$ which on treatment with HCl yielded $\text{10}$.     

Enantio- and diastereomerically pure threo-homoallylic alcohols via highly stereoselective reduction of α-methyl-β,γ-unsaturated ketones

Reduction of α-methyl-β,γ-unsaturated ketones with L-Selectride proceeded with high $\text{threo}$-selectivity to afford $\text{threo}$-β-methyl homoallylic alcohols of high enantio- and diastereomerical purities.     

Synthesis of the alkaloids julandine and ipalbidine-use of silicon (IV) chloride

Titanium (IV) chloride and silicon (IV) chloride with high oxygen affinity are the best Lewis acid catalysts, of a number tested, for cyclisation of an enamine-ketone (1) leading to the alkaloid, julandine (2); cyclisation of (6) in methanol solution without catalyst yields $\text{O}$-methylipalbidine (7) .     

13C NMR of carbonyl compounds. 3. Structure and dynamics of protonated enones and dienones

The unsaturated ketones $\text{1}$1 – $\text{10}$10 were protonated at low temperatures and studied by dynamic ¹³C NMR spectroscopy. Four interconverting stereoisomers were detected which differ in their conformation with respect to the CO and CC (enone) single bond.     

μ-Bis(cyanotrihydroborato)-tetrakis(triphenylphosphine) dicopper(I). A new,selective, pH dependent reducing agent

The title compound selectively reduces acid chlorides to aldehydes under neutral conditions and aldehydes and ketones to alcohols in acidic media. 4-$\text{tert}$-Butylcyclohexanone is reduced to the $\text{trans}$ alcohol with a high degree of stereoselectivity (94:6).     

Synthesis and intramolecular cyclisation of ortho-hydroxy-2,3,3,3-tetrafluoropropiophenone. Formation of 3-fluoro-4-hydroxycoumarin

Acidic hydrolysis of 1-(o-methoxyphenyl)pentafluoropropene $\text{1}$ gave o-hydroxy-2,3,3,3-tetrafluoropropiophenone $\text{2}$ and o-methoxy-2,3,3,3-tetrafluoropropiophenone $\text{3}$. Compound $\text{2}$ when treated with aqueous potassium hydroxide or methanolic sodium methoxide gave 3-fluoro-4-hydroxycoumarin $\text{4}$. Structure of $\text{4}$ has been established by spectral means and some chemical reactions. The cyclisation mechanism of $\text{2}$ is discussed.     

A new method for preparing 1-phenylthio-1-trimethylsilylalkanes: the preparation of α-silylcarbanions and olefins.

1-Phenylthio-1-trimethylsilylalkanes(1) are prepared in high yield from 1,1-bis(phenylthlo)acetals(2) by reaction with lithium naphthalenide(3) followed by chlorotrimethylsilane. α-Silylcarbanions are formed from the alkanes(1) and lithium naphthalenide(3). Subsequent reaction with carbonyl compounds gave the olefins(4) $\text{via}$ the Peterson reaction.     

The palladium-catalysed reductive addition of aryl iodides to propargyl alcohols: a route to /gg,/gg-diaryl allylic alcohols

The reaction of aryl iodides with ethynyl and arylethynyl,dialky $\text{l}$ carbinols in the presence of the tri- or dialkylammonium formate-palladium reagent provides a convenient route to γ,γ-diarylallylic alcohols. In the presence of arylethynyl,alkylcarbinols a lack of regioselectivity was observed and mixtures of ß,γ-, γ,γ-diarylallylic alcohols, and α,ß-unsat$\text{u}$ rated ketones were obtained.