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cis- and trans-1,3-Dimethylindan-5-amines have been prepared and allowed to react with hexa-carbonylchromium. The stereochemistry of the tricarbonylchromium complexes so obtained is discussed.

Reactions of π-allylpalladium compounds with sodium acetylacetonate, sodium malononitrile, and sodium ethylacetoacetate in dimethyl sulfoxide solution give diallyl substitution products. Reaction of the acetylacetonate complexes with carbon monoxide in benzene give mono- allyl substitution products. Application of these reactions to the π- allyl complexes from 1-acetyl-4-t-butylcyclohex-1-ene and from 3-oxo 4- ene steroids in an attempt to examine the stereochemistry of ligand transfer gave no substitution products.

Reaction of the π-allylpalladium compounds derived from some 3-oxo 4- ene steroids with malonate ion gives dialkyl (3-oxo-steroid-4-en-6β- yl)malonates in high yield and with complete stereo-specificity. The 6β-malonates can be epimerized to give the more stable 6α-epimers or decarboalkoxylated to give the corresponding acetic acid derivatives.

Reaction of 5-chloromethyl-3-phenyl-4,5-dihydroisoxazole with potassium t-butoxide in dimethyl sulphoxide gives 4-phenyl-2-oxa-3- azabicyclo[3,1,0]hex-3-ene in high yield and reaction of the 5-(1?- chloroethyl) homologue gives high yields of the diastereoisomeric 6- methyl derivatives of the bicyclic system. Some unsuccessful attempts to convert these bicyclic compounds into substituted cyclo-propanols and cyclopropenes are described.

Hydrogenolysis of the propellanes tricyclo[4,4,1,01,6]undecane and tricyclo[4,3,1,01,6]decane gives similar stereochemical ratios of products for reactions carried out either in acetic acid solution with a platinum oxide catalyst or over supported metal catalysts in the vapour phase. Almost equal amounts of cis- and trans-1- methylbicyclo[4,4,0]decanes are formed from the former, whereas cis-1- methylbicyclo[4,3,0]nonane predominates from reaction of the tricyclodecane. It is proposed that reaction of the highly strained propellanes over metal catalysts involves metal insertion reactions even for reactions over platinum in acetic acid solution. Deuterium incorporation studies are described which support this proposal.

Hydrogenolysis of 3-methylnortricyclene over platinum in acetic acid solution leads to the formation of almost equal amounts of 7-methylnorbornane and exo-2-methylnorbornane with much smaller amounts of the endo-2-methyl compound. In contrast, reactions over supported metal catalysts in the vapour phase lead to a predominance of the 2-methyl compounds. Similar trends have been observed in the hydrogenolyses of 3-cyclohexyl- and 3-acetoxy-nortricyclenes.

Reaction of 1,8-cineole with hydrogen over supported platinum and palladium catalysts gives mixtures of cis- and trans-p-menthanes. p- Cymene is also produced from reactions at higher temperatures over palladium on pumice. Studies of reactions of potential intermediates and of the reaction of 1,8-cineole with deuterium have led to a proposed mechanism for the reaction.

The 13C n.m.r, spectra of a series of tricarbonyl(arene)chromiums have been determined. The spectra are interpreted in terms of electronic effects of the substituent together with effects arising from con- formational preferences of the tricarbonylchromium residue. No evidence for kinetic restriction of rotation could be found for any of the complexes at temperatures greater than -60.

The products of addition of thioacetic acid to norbornadiene, and of tributyltin hydride and triphenyltin hydride reduction of exo-2-bromo- anti-7-thioacetoxynorborn-5-ene (7), and trans-5-bromo-3- thioacetoxynortricyclene (8), have been examined. In contrast to results obtained with the corresponding acetoxy compounds, the product ratios vary with the reducing reagent and the starting material and the ratio of (rate of rearrangement)/(rate of hydrogen atom abstraction) is significantly less for the thioacetoxy substituted radicals.

Reaction of chlorobenzene with crotonic acid under Friedel-Crafts conditions gives an unexpectedly high proportion of 4-chloro-3- methylindan-1-one together with the expected 6-chloro-3-methylindan-1- one. Hydrogenolysis of the tertiary alcohols which result from addition of methylmagnesium iodide to these compounds gives predominantly cis-4- and -5-chloro-1,3-dimethylindanes with only small amounts of the trans- isomers.

The steroidal 1,4-diphosphines 3α- and 3β-diphenylphosphino-2a-(2'-diphenylphosphinoethyl)-5α-cholestanes and their 5H-benzo[b] phosphindole derivatives have been prepared and shown to be useful ligands in asymmetric hydrogenation reactions. Interestingly the 3α- and 3β-derivatives lead to opposing enantioselection preferences when used in these reactions. A steroidal 1,3-diphosphine, 3α-diphenylphosphino-2α-diphenylphosphinomethyl-5α-cholestane, has been prepared as a mixture containing some of the 3β-epimer. The 3α-1,3-diphosphine led to similar enantioselection in hydrogenation reactions as the 3α-1,4-diphosphine, and a model is proposed to explain the sense of the enantioselectivity in the 1,4- and 1,3-diphosphines. A steroidal 1,6-diphosphine has also been prepared but leads to lower optical yields in the hydrogenation reactions. These ligands have been shown to lead to only poor to moderate optical yields when used in asymmetric carbon-carbon bond forming reactions.

Reaction of hydrogen cyanide with a wide range of aliphatic dienes in the presence of nickel(0) catalysts leads to rearrangement of the diene and formation of β,γ -unsaturated nitriles in moderate to very high yields. The mechanism of reaction is discussed in terms of π-allyl-nickel intermediates.

Exposure of crystalline β- cyclodextrin complexes of aldehydes to hydrogen cyanide gives cyanohydrins in moderate to good yields. The hydrocyanation reaction displayed enantioselection, and the cyanohydrins were formed with optical yields in the range from 0 to 33%.

The regioselectivity of reaction of tricarbonyl (1,1- dimethylindane )chromium with selected electrophiles and nucleophiles has been shown to be influenced by the preferred conformation of the tricarbonylchromium group. Nucleophiles preferentially react at carbon atoms eclipsed by a chromium-carbonyl bond and electrophiles at carbon atoms in staggered positions. When similar reactions were attempted with some chelated arenechromium dicarbonyl phosphorus compounds only low yields of substitution products were obtained.

(+)-(3S,4S)-Tetrahydrofuran-3,4-diyl bis(diphenylphosphinite) [(+)-diphin] has been synthesized and its efficiency as a ligand in asymmetric hydrogenation, hydrocyanation and hydroformylation compared with closely related diphosphine, diphosphinite and diphosphite ligands.

Reactions of (E)-3,3-dimethyl(1,2-D2)but-1-ene with hydrogen cyanide and of (E)-3,3-dimethyl-(1-D)but-1-ene with deuterium cyanide have been shown to proceed in a completely stereospecific cis fashion when a catalyst system based on Pd(diop)2 was used. Reaction between 4-t-butylcyclo-hexene and deuterium cyanide with the catalyst system gave only the equatorial nitriles trans- 4-t-butylcyclohexane-1-carbonitrile and cis-3-t-butylcyclohexane-1-carbonitrile with cis incorporation of deuterium. Use of a catalyst system based on Ni[P(OPh)3]4 and zinc chloride led to significant amounts of isotopic exchange and rearrangement. These results are compared with those from hydroformylation of the olefins, and the mechanism of hydrocyanation is discussed.

[(+)-(diop)]2Pd and [(+)-(diop)]2Ni have been prepared and used as catalysts for the asymmetric addition of hydrogen cyanide to alkenes. The corresponding complex of platinum with diop has also been prepared and found to be less useful as a catalyst as were the complexes of these three metals with other chelating diphosphines.

Reactions of π-allylpalladium complexes of α,β-unsaturated ketones and esters with nucleophiles occur regioselectively at the γ-carbon atom to give high yields of γ-functionalized products. The E/Z-stereochemistry of the products is discussed in relation to the syn/anti- stereochemistry of the π-allylpalladium compounds and the reactivity of the latter compounds is discussed in terms of their 1H and 13C N.M.R. spectra.

Reactions of π-allylpalladium compounds with the 1,3-dipolar species, benzonitrilioanilide and benzonitrile N-oxide, give low yields of five- membered ring heterocyclic compounds. It is proposed that the π- allylpalladium compounds decompose to give allylic halides which then react with the dipolar species to give heterocyclic products.

The 13C chemical shifts of some triphenyl-phosphine and -arsine dicarbonyl(arene)chromiums are reported. The shifts are discussed in terms of a deshielding effect on the arene ring carbons trans to the Group 5 atom in the preferred conformations of these molecules.

The regiochemistry of hydroformylation of alkenes can be controlled by the use of bulky silyl groups attached to the alkene. Use of the t-butyldiphenylsilyl group leads to almost total regiocontrol and the method has been applied to the synthesis of aldols.

Hydroformylation and hydrocyanation of 2-methylhex-1-en-3-yne surprisingly both involve addition to the alkyne leading to the formation of formyl- and cyano-buta-1,3-dienes whose reactivity in Diels-Alder and ene-type reactions has been investigated.

A range of aryl, alkyl and heterocyclic aldehydes have been treated with hydrogen cyanide in the presence of the 'Inoue' catalyst, (R,R)- or (S,S)-cyclo [phenylalanylhistidyl]. Most aryl aldehydes with electron-donating substituents in the m- or p-positions give high enantiomeric excess (e.e.) values (≥80%) but aryl aldehydes with strong electron-withdrawing substituents gave moderate e.e. values (≤50%). These moderate values are believed to be due to partial racemization of the product cyanohydrins in the presence of the mildly basic catalyst. In contrast to the reactions of aryl aldehydes , reactions of alkyl aldehydes and of ketones gave low e.e. values (≤30%) and an explanation is proposed.

The hydrocyanation of a range of amino alkyne derivatives has been studied by using nickel-based catalyst systems. The phthalimido derivatives have been shown to give good yields of unsaturated cyano amine derivatives, and some of these have been converted into both saturated and unsaturated amino acids.

The regioselectivity of hydrocyanation of a range of alkynols using nickel-based catalyst systems involving either triphenyl phosphite or α,α′-bis(diphenylphosphino)-o-xylene (phmep) has been investigated. The regioselectivity of the hydrocyanations involving the phosphine catalyst reflected dominant steric effects whereas results from the phosphite catalyst system showed some evidence for chelation control. Yields of nitriles from reactions based on the phosphite system were variable, whereas moderate to good yields of distilled products could be obtained consistently by using the phosphine -based system. An explanation for this variation in yield is proposed.

A series of cyclic dipeptides has been prepared and evaluated as catalysts for the asymmetric hydrocyanation of benzaldehyde and 3-phenoxybenzaldehyde. Cyclo -(R,R)- or (S-S)-( phenylalanylhistidyl ), previously reported by Inoue and his coworkers, has proven to be the most effective catalyst, giving high preparative and optical yields under appropriate conditions.

A number of new arenetricarbonylchromium compounds have been synthesized in which the arene ring is substituted with a number of large groups such as t-butyl. Also prepared were the Ph3PCr(CO)2 and (PhO)3PCr(CO)2 analogues of these compounds and of more lightly substituted arenes, and a number of chelate compounds incorporating a short chain attached at C1 of the arene and bonded to chromium by phosphine, phosphite or phosphinite phosphorus atoms. The 13C n.m.r. spectra of these compounds have been recorded, and examined for evidence of stereo-specific influences of phosphorus on the chemical shifts of the arene ring carbons, but no such effects were found. 31P n.m.r. chemical shifts are also reported for these compounds.