111957-98-3

Preparation of sila-β-ionone (14) was possible by a novel route with yields nearly 5 times higher than before, with the formerly unknown 1,1,3-trimethyl-1-silacyclohexanone-2 (6) as a key substance.The nine reaction steps may be seen from Scheme 1. 2-Ethinyl-1,1,3-trimethyl-1-silacyclohexan-2-ol (7) could not be dehydrated to give the analogous silacyclohexene derivative 9.But dehydration was successful in the case of 2-(1-butin-3-ol) substituents; here only the ring but not the chain hydroxyl group was eliminated. - Keywords: Sila-perfumes; Silacyclohexanon-2; Sila-β-ionone

A highly enantio- and stereoselective synthetic strategy for both syn-and anti-1,3-polyols has been developed. The sequence involves iterative Jacobsen's hydrolytic kinetic resolution (HKR), diastereoselective iodine-induced electrophilic cyclization, and ring-closing metathesis (RCM). This protocol has subsequently been utilized for the synthesis of cryptocarya diacetate, a natural product with broad range of biological activity.

The synthesis of five diastereomeric model compounds incorporating the C32-C46 segment of the antitumor marine natural product hemicalide has been achieved through a convergent approach relying on the 1,4-addition of an alkenyl boronate to an α,β-unsaturated δ-lactone followed by α-hydroxylation of an enolate and a Julia-Kocienski olefination. Comparison of the 1H and 13C NMR data of the model compounds with those of hemicalide enabled the assignment of the relative configuration of the C36-C42 subunit. (Chemical Equation Presented).

-

The hydrophilic palladium complex efficiently catalyzes the allylation of carbonyl compounds with allyl chlorides or allyl alcohols and SnCl2 under aqueous-organic biphase conditions, which allow us easily to separate the product and to recover the organic solvent from the reaction mixture.

A highly stereoselective synthesis of (+)-cryptocarya diacetate is achieved through our recently developed strategy for the construction of 1,3-diols via Prins cyclisation. The route relies mainly on the reductive cleavage of allylic ethers, ozonolysis and Wittig olefination along with Prins cyclisation.

The convergent synthesis of candidate stereoisomers of the natural product arenolide was accomplished using recently developed catalytic boron-based reactions. Comparison of the spectral data for candidate structures with that reported for the authentic natural product revealed the likely stereostructure of the natural compound.

In this communication, a concise and efficient synthetic route for the synthesis of (–)-Cephalosporolide D in enantioselective way has been described. In this synthesis, Mitsunobu esterification and Ring Closing Metathesis (RCM) for macrocyclic ring formation have been applied as key steps.

We report a copper-catalyzed enatiotopic-group-selective allylation of gem-diborylalkanes with allyl bromides. The combination of copper(I) bromide and H8-BINOL derived phosphoramidite ligand proved to be the most effective catalytic system to provide various enantioenriched homoallylic boronate esters, containing a boron-substituted stereogenic center that is solely derived from gem-diborylalkanes, in good yields with high enantiomeric ratios under mild conditions. Experimental and theoretical studies have been conducted to elucidate the reaction mechanism, revealing how the enatiotopic-group-selective transmetalation of gem-diborylalkanes with chiral copper complex occurs to generate chiral α-borylalkyl-copper species for the first time. Additional synthetic applications to the synthesis of various chiral building blocks are also included.

In this article, we investigated the I2-promoted cyclic dialkyl ether formation from 6-membered oxanickelacycles originally reported by Hillhouse. A detailed mechanistic investigation based on spectroscopic and crystallographic analysis revealed that a putative reductive elimination to forge C(sp3)-OC(sp3) using I2 might not be operative. We isolated a paramagnetic bimetallic NiIII intermediate featuring a unique Ni2(OR)2 (OR = alkoxide) diamond-like core complemented by a μ-iodo bridge between the two Ni centers, which remains stable at low temperatures, thus permitting its characterization by NMR, EPR, X-ray, and HRMS. At higher temperatures (>-10 °C), such bimetallic intermediate thermally decomposes to afford large amounts of elimination products together with iodoalkanols. Observation of the latter suggests that a C(sp3)-I bond reductive elimination occurs preferentially to any other challenging C-O bond reductive elimination. Formation of cyclized THF rings is then believed to occur through cyclization of an alcohol/alkoxide to the recently forged C(sp3)-I bond. The results of this article indicate that the use of F+ oxidants permits the challenging C(sp3)-OC(sp3) bond formation at a high-valent nickel center to proceed in good yields while minimizing deleterious elimination reactions. Preliminary investigations suggest the involvement of a high-valent bimetallic NiIII intermediate which rapidly extrudes the C-O bond product at remarkably low temperatures. The new set of conditions permitted the elusive synthesis of diethyl ether through reductive elimination, a remarkable feature currently beyond the scope of Ni.

A very concise total synthesis of (+)-brefeldin C starting from 2-furanylcyclopentene is described. This approach is based on an unprecedented enantioselective radical hydroalkynylation process to introduce the two cyclopentane stereocenters in a single step. The use of a furan substituent allows a high trans diastereoselectivity to be achieved during the radical process and it contains the four carbon atoms C1–C4 of the natural product in an oxidation state closely related to the one of the target molecule. The eight-step synthesis requires six product purifications and it provides (+)-brefeldin C in 18 % overall yield.

A mechanistic investigation of the carbohydrate/DBU cocatalyzed enantioselective diboration of alkenes is presented. These studies provide an understanding of the origin of stereoselectivity and also reveal a strategy for enhancing reactivity and broadening the substrate scope.

The invention relates to [1,3]thiazin-2-amine compounds as well as applications and pharmaceutical compositions thereof, and belongs to the field of BACE (beta-site amyloid precursor protein cleavingenzyme) inhibitors. The [1,3]thiazid-2-amine compounds are compounds, pharmaceutically acceptable salts, stereoisomers, solvates, or prodrugs represented by a formula (I), and the formula (I) is shownin the description. The [1,3]thiazin-2-amine compounds provided by the invention have good inhibiting effects on BACE, and can be used for the preparation of medicines for treating neurodegenerativediseases such as alzheimer diseases.

Mechanistic studies on Cu-catalyzed asymmetric additions of alkylzirconocene nucleophiles to racemic allylic halide electrophiles were conducted using a combination of isotopic labeling, NMR spectroscopy, kinetic modeling, structure-activity relationships, and new reaction development. Kinetic and dynamic NMR spectroscopic studies provided insight into the oligomeric Cu-ligand complexes, which evolve during the course of the reaction to become faster and more highly enantioselective. The Cu-counterions play a role in both selecting different pathways and in racemizing the starting material via formation of an allyl iodide intermediate. We quantify the rate of Cu-catalyzed allyl iodide isomerization and identify a series of conditions under which the formation and racemization of the allyl iodide occurs. We developed reaction conditions where racemic allylic phosphates are suitable substrates using new phosphoramidite ligand D. D also allows highly enantioselective addition to racemic seven-membered-ring allyl chlorides for the first time.1H and2H NMR spectroscopy experiments on reactions using allylic phosphates showed the importance of allyl chloride intermediates, which form either by the action of TMSCl or from an adventitious chloride source. Overall these studies support a mechanism where complex oligomeric catalysts both racemize the starting material and select one enantiomer for a highly enantioselective reaction. It is anticipated that this work will enable extension of copper-catalyzed asymmetric reactions and provide understanding on how to develop dynamic kinetic asymmetric transformations more broadly.

Catalytic enantioselective conjunctive cross-coupling between 9-BBN borate complexes and aryl electrophiles can be accomplished with Ni salts in the presence of a chiral diamine ligand. The reactions furnish chiral 9-BBN derivatives in an enantioselective fashion and these are converted to chiral alcohols and amines, or engaged in other stereospecific C?C bond forming reactions.

The present invention relates to a pyrrolopyridine derivative expressed as chemical formula 1, specifically a compound including a substituent group having an oxatane group in R1, its stereoisomer or racemic body, their pharmaceutically acceptable salts or their solvate, a manufacturing method thereof, and an antivirus composition containing the same as an active ingredient, wherein the compound expressed as chemical formula 1 has excellent selectivity and physiological activity with respect to wild type or resistant HIV-1 and therefore can be used as a remedy for AIDS.

An efficient synthetic method for preparing enantioenriched secondary borylalkanes has been achieved through a copper-catalyzed regio- and enantioselective hydroallylation of alkenyl boronates and boramides employing hydrosilanes and allylic phosphates. In the presence of a copper catalyst with a chiral Walphos ligand, a range of alkenylboron compounds with an aryl, heteroaryl, or alkyl substituent produced secondary homoallylic alkylboron compounds in good yields and with high enantioselectivities up to 99% ee. The utility of the resulting alkylboronates was demonstrated in an efficient synthesis of (S)-massoialactone.

The preparation of 2,6-substituted piperidine derivatives through diastereoselective C-H functionalization of corresponding nitrogen heterocycles represents an appealing protocol and yet remains a formidable challenge. Here, we describe a stereochemically complementary oxidative C-H functionalization of N-carbamoyl tetrahydropyridines with a wide variety of building blocks, providing either the cis- or trans-2,6-substituted piperidines with diverse patterns of functionalities. The mild metal-free process exhibits excellent regio- and diastereoselectivities as well as functional group tolerance. The synthetic utilities in natural product and analogue syntheses are also described.

A concise and facile synthesis of (3R,5S)-5-hydroxy-de-O-methyllasiodiplodin has been demonstrated in 12 steps starting from methylacetoacetate and (±)propylene oxide. The key reactions involved are Jacobsen's hydrolytic kinetic resolution, Sharpless asymmetric epoxidation, Mitsunobu, and ring closing metathesis reaction for the construction of macrolactone with two chiral substitutions on it.

A convergent and stereoselective synthesis of cochliomycin A, a 14-membered resorcyclic acid lactone, based on chiron approach is described. The key reactions involved olefin cross-metathesis and sodium hydride promoted one-pot intramolecular lactonization. l-Arabinose was used as a chiral pool material for the construction of the key fragment.

Herein, we describe the enantioselective construction of the 12-membered macrocyclic pyrrole core of marineosin A in 5.1 % overall yield from (S)-propylene oxide. The route features a key Stetter reaction to install a 1,4-diketone, which is subjected to Paal-Knorr pyrrole synthesis and ring-closing metathesis to afford the macrocycle. A divergence point in the synthetic scheme also enabled access to a highly functionalized spiroaminal model system through an acid-mediated hydroxy oxo amide cyclization strategy. Copyright

The synthesis of three tetrahydroxyindolizidines and one tetrahydroxypyrrolizidine related to natural hyacinthacines B and their biological evaluation as glycosidase inhibitors is reported. The target molecules were obtained through highly stereoselective cycloadditions between sugriched allylic and homoallylic alcohols. This allowed the installation of a methyl group at C5 - a common feature of many natural hyacinthacines - with high control over the stereoselectivity. The new compounds inhibit amyloglucosidase from Aspergillus niger and β-glucosidase from almonds. Compound 1 is a competitive inhibitor of amyloglucosidase and shows a fair selectivity towards this enzyme. The presence of C5-Me substitution in indolizidines 2 and 3 slightly diminishes the inhibitory activity towards amyloglucosidase whereas it improves the inhibitory properties towards β-glucosidase. Cycloaddition between a carbohydrate-derived nitrone and suitable chemoenzymatically prepared enantioenriched allylic and homoallylic alcohols allowed the straightforward synthesis of three tetrahydroxyindolizidines and one tetrahydroxypyrrolizidine related to natural hyacinthacines B. They inhibit amyloglucosidase from Aspergillus niger and β-glucosidase from almonds. Copyright

Two new mycolactones, mycolactones S1 and S2, were isolated from culture agar of Mycobacterium ulcerans subsp. shinshuense. Their structures were established in a three-step procedure: (1) probable structures were speculated from MS analysis; (2) candidates were synthesized; (3) HPLC profiles were established for identification of the natural products. Newly isolated mycolactones correspond to the oxidized forms of mycolactone A/B, the causative toxin of Buruli ulcer, isolated from Mycobacterium ulcerans.

The substrate spectrum of the inverting alkylsulfatase Pisa1 was investigated using a range of sec-alkyl sulfate esters bearing aromatic, olefinic and acetylenic moieties. Perfect enantioselectivities were obtained for substrates bearing groups of different size adjacent to the sulfate ester moiety. Insufficient selectivities could be doubled by using dimethyl sulfoxide (DMSO) as co-solvent. Hydrolytically unstable benzylic sulfate esters could be sufficiently stabilised by introduction of electron-withdrawing substituents. Overall, Pisa1 appears to be a very useful inverting alkylsulfatase for the deracemisation of rac-sec-alcohols via enzymatic hydrolysis of their corresponding sulfate esters, which furnishes homochiral products possessing the 'anti-Kazlauskas' configuration. Copyright

An enantioselective total synthesis of aspergillides A and B has been accomplished based on a unified strategy, wherein a hydroxy-directed, highly chemoselective olefin cross-metathesis and a diastereoselective intramolecular oxa-conjugate cyclization were employed to forge the 2,6-substituted tetrahydropyran substructure.

An enantioselective total synthesis of aspergillides A and B has been accomplished on the basis of a unified synthetic strategy that exploits stereodivergent intramolecular oxa-conjugate cyclization and Yamaguchi macrolactonization.

The first simple and efficient total synthesis of sporostatin has been accomplished in five steps starting from (S)-propylene oxide. The synthesis utilizes simple reactions such as esterification, cross-metathesis, and intramolecular Friedel-Crafts reacti

(Chemical Equation Presented) A concise and enantioselective total synthesis of (+)-aigialospirol is described here, featuring the first complex natural product synthesis that employs a cyclic ketal-tethered ring-closing metathesis strategy and an unexpected stereoselective epimerization of a benzylic hydroxyl group. The 15-step synthetic sequence illustrates the proof-of-concept that such an approach can be competitive with the classical spiroketal formation in the natural product synthesis.

The remarkable versatility and selectivity of the 10-(trimethylsilyl)-9- borabicyclo[3.3.2]decanes (10-TMS-9-BBDs) in the allyl- and crotylboration of representative aldehydes are reported. The new reagents are prepared through air-stable crystalline pseudoephedrine borinic ester complexes of the 10-TMS-9-BBDs (4), which are available in 63% overall yield from B-MeO-9-BBN through a simple two-step procedure. These complexes 4 are directly converted to the corresponding B-allyl-10-TMS-9-BBDs (1) with allylmagnesium bromide, which either can be isolated (98%) or used in situ for the allylations. The remarkable enantioselectivity (96 to ≥99% ee) of these reagents in the rapid (3 h), asymmetric allylboration process at -78 °C is only slightly diminished when it is conducted at 25 °C, a phenomenon attributable to its rigid bicyclic structure. In addition to providing the homoallylic alcohols 6 efficiently (68-80%), the procedure also permits the efficient recovery of 4 (68-84%) for the direct regeneration of 1. Alternatively, an oxidative workup procedure can be used for the preparation of 6. The reagent gives predictable stereochemistry and exhibits an extremely high level of reagent control in the allylboration of D-glyceraldehyde acetonide. A simple and efficient procedure has been developed for the preparation of all four geometric and enantiomeric isomers of the B-crotyl-10-TMS-9-BBDs (10) from optically pure enantiomers of B-MeO-10-TMS-9-BBD (3). These reagents 10 also add rapidly (3 h) and efficiently to representative aldehydes at -78 °C, providing ready access to all four of the possible stereoisomers of the β-methyl homoallylic alcohols 12-15 (69-92%) in high dr (≥98:2) and ee (94-99%).

A new synthesis of (+)-brefeldin C featuring a Bolm desymmetrisation reaction, a B-alkyl Suzuki-Miyaura cross-coupling and a Carreira alkynylation reaction as the key steps is reported.

The present invention generally relates to nicotinic compounds, in the form of aryl substituted olefinic compounds, as well as pro-drug, N-oxide, metabolite and pharmaceutically acceptable salt forms thereof. Methods of modulating neurotransmitter release via administration of the compounds, pro-drugs, N-oxides and/or pharmaceutically acceptable salts are also disclosed.

An eleven-step synthesis of the title compound (1) from biocatalytically-derived and enantiomerically pure 'building blocks' alcohol (R)-(-)-9 and ester 13 is described. Attempts to construct the twelve-membered lactone ring of cladospolide A in a direct manner by using a ring-closing metathesis (RCM) reaction failed. However, a ten-membered lactone 19, could be constructed by such means and this was then subject to a two-carbon homologation sequence involving, inter alia, Wadsworth-Horner-Emmons and Yamaguchi lactonisation reactions in the closing stages of the synthesis. The impact of substituent stereochemistries and protecting groups on the RCM reaction leading to various ten-membered lactones is also described.

A rationally designed mechanistic approach to anti-Markovnikov olefin hydrofunctionalization and its application to the synthesis of heterocycles are described. Porphyrin-rhodium complexes have been shown to exhibit remarkable reactivity and selectivity for each step of the proposed catalytic cycle (see scheme). A critical step of this reaction sequence is a new, facile, and remarkably general carbon-heteroatom bond-forming reductive elimination.

The present invention generally relates to nicotinic compounds, in the form of aryl substituted olefinic compounds, as well as pro-drug, N-oxide, metabolite and pharmaceutically acceptable salt forms thereof. Methods of modulating neurotransmitter release via administration of the compounds, pro-drugs, N-oxides and/or pharmaceutically acceptable salts are also disclosed.

Whole lyophilised cells of Rhodococcus ruber DSM 44541 were employed for the oxidative kinetic resolution of sec-alcohols using acetone as hydrogen acceptor. The enantioselectivity of this process could be controlled effectively by introducing C-C multiple bonds into substrates, which were inefficiently recognised, in particular short-chain (ω-1)-alcohols and (ω-2)-analogs. Thus, the enantioselectivities of rac-2-pentanol (E=16.8) and rac-3-octanol (E=13.3) were significantly improved by introducing a C=C bond adjacent to the alcohol moiety to give racemic (E)-pent-3-en-2-ol and 4-(E)-octen-3-ol, which were resolved with excellent selectivities (E >100 and 50, respectively). In addition, it was found that high stereodifferentiation between the E- and Z-configured double bonds occurred, as the corresponding (Z)-isomers were not converted. Similar selectivity-enhancing effects were observed with acetylenic analogs.

The enantiomerically pure cis-1,2-dihydrocatechol 7, which is obtained by microbial oxidation of chlorobenzene, has been converted, via a sequence of reactions including ring-closing metathesis and Yamaguchi lactonisation steps, into the natural product (-)-cladospolide A (1).

Crosslinked polymer-supported chiral N-sulfonylamino alcohols 5-8 have been prepared by suspension polymerization of enantiopure N-sulfonylamino alcohol monomers 1-4 with styrene and divinylbenzene. Polymer-supported chiral allylboron reagents were prepared from the polymeric chiral ligands. Enantioselective additions of the polymer-supported allylboron reagents to aldehydes and N-(trimethylsilyl)imines have been successfully carried out in the heterogeneous system. The corresponding optically active homoallyl alcohols and homoallylamines were obtained in high yields with high enantioselectivities (up to 95% ee) which are almost the same as those obtained from homogeneous analogues. The polymer-supported chiral ligands used were recovered easily and can be reused without any loss of activity.

-

Acrylic esters of homoallylic alcohols prepared in 92-97% ee via the asymmetric allylboration of appropriate aldehydes with B- allyldiisopinocampheylborane, when refluxed in dichloromethane in the presence of 10 mol% of Grubbs' catalyst provided the natural enantiomers of (S)-(+)-parasorbic acid, (R)-(-)-massoia lactone, and (R)-(+)goniothalamin. (S)-(-)-Hexadecanolide was prepared by hydrogenating the corresponding lactenone synthesized using the above sequence. (C) 2000 Elsevier Science Ltd.

Readily prepared and stable (±)-isopinocampheyldichloroborane [(±)-IpcBCl2] was conveniently used for the stepwise hydroboration of two different alkenes using the in situ reduction-hydroboration protocol to give mixed trialkylboranes, IpcBR'R2. Convenient elimination of α-pinene from these trialkylboranes by treatment with an aldehyde, RCHO, provided the borinate ester, R1R2BOCH2. This intermediate was readily converted into the unsymmetrical ketones, R1OR2, in high yields and purity, by an established method. This methodology was successfully applied to the synthesis of enantiomerically pure spiroketals using optically pure TBS ether protected homoallylic alcohols as the alkenes for stepwise hydroboration.

Satisfactory kinetic determinations of several aliphatic 1,3-diols were difficult to obtain. Moreover the product distributions from each of these substrates suggest complex parallel mechanisms. However, the elimination kinetic of 2,4-dimethyl-2,4-pentanediol has been measured over the temperature range of 419.7-459.9 °C and pressure range of 47-115 torr. The reaction carried out by employing a static system, in seasoned vessel, and in the presence of the free-radical inhibitor propene, proved to be homogeneous, unimolecular, and follows a first-order rate law. The products are acetone, isobutene, and H2O. The rate coefficient is expressed by the following Arrhenius equation: log k1(s-1) = (12.53±0.58)-(217.3±8.0) kJ mol-1 (2.303 RT)-1. The pyrolytic elimination of this substrate is believed to proceed through a concerted six-membered cyclic transition-state type of mechanism.

Iodocyclisations of E-homoallylic tosylamides 7 lead to excellent yields of either 2,5-trans- or 2,5-cis-3-iodopyrrolidines (10 or 11), depending upon the reaction conditions.

Intramolecular cycloadditions of the nitrones 9 and 14 show moderate to good stereoselections in favour of the cis-fused diastereoisomers 10 or 16, respectively.

Upon PET reaction, amines of type 1 undergo efficient cyclisations to produce pyrrolidines and piperidines. Mechanistically, involvement of delocalised α-silylmethyl amine radical cation as reactive intermediate in such cyclisations are described.

Seventeen unsaturated hydroperoxides have been converted by treatment with mercury(II) acetate and/or mercury(II) nitrate into nineteen new mercuriated cyclic peroxides and by subsequent demercuriation with alkaline sodium borohydride, six new mercury-free peroxides have been isolated. The results greatly extend the range of such reactions and provide information about the stereoselectivities and relative ease of several different modes of cycloperoxymercuriation. It is suggested that the reactions with mercury(II) acetate are kinetically controlled whereas those with mercury(II) nitrate show a component of thermodynamic control of product distribution.

In the absence of magnesium salts (from the synthesis of the reagents), our chiral B-allylditerpenylborane reagents (Ter2*BCH2CH=CH2), 1-3) react with representative aldehydes (RCHO, R=Me, n-Pr, i-Pr, t-Bu, vinyl, and Ph) practically instantaneously at -100 deg C to give homoallylic alcohols (R*CH(OH)CH=CH2) with optical purities approaching 100percent ee.The exceptional reaction rate achieved at -100 deg C indicates that these allylborations are among the fastest reactions presently known to the organic chemist.The short reaction time adopted (dIpc2BAll, d1) give homoallylic alcohols of >/= 98percent ee and B-allylbis(2-isocaranyl)borane (2-dIcr2BAll, 3) provides alcohols of >/= 99percent ee.The enantioselectivities (>/= 99percent ee) achieved in allylboration by the reagent 3 are essentially perfect, making this one of the most stereoselective reactions currently known in organic chemistry.

A series of 5- and 6-substituted cyclophosphamide analogues has been prepared, and their 31P NMR kinetics of phosphoramide mustard (PDA) release and in vitro and in vivo cytotoxicity have been evaluated. cis-4-Hydroxy-5-methoxycyclophosphamide equilibrated very slowly and to a minor extent with the ring-opened aldophosphamide analogues in aqueous buffer; release of PDA was observed to a minor extent and only at high (1 M) buffer concentrations.This analogue was essentially inactive in vitro against L1210 and P388 leukemia cells. 6-Phenylcyclophosphamide and its 4-hydroperoxy derivative were potent inhibitors of blood acetylcholinesterase and were lethal at therapeutic doses in mice.In contrast, 4-hydroperoxy-6-(4-pyridyl)cyclophosphamide did not inhibit acetylcholinesterase and showed significant antitumor activity in vitro and in vivo against both wild-type and cyclophosphamide-resistant L1210 leukemia.The 4-hydroperoxy-6-arylcyclophosphamides were generally active in vitro against both wild-type and cyclophosphamide-resistant L1210 and P388 cells, and several analogues showed significant activity in vivo.Suprisingly, there was no correlation between antitumor activity in vitro and the rate of PDA release in aqueous buffer.Several compounds that showed essentially no release of PDA in aqueous buffer over several hours were highly cytotoxic to leukemia following a 1-h exposure in vitro.These results show that activated cyclophosphamide analogues substituted at the 6-position are not-cross-resistant in these leukemia cell lines, and that a specific intracellular activation mechanism may be catalyzing PDA release in these analogues.

3-phenylthio-2-(trimethylsilymethyl)propene is a convenient conjunctive reagent for the preparation of methylenecyclohexanes via a [3+3] annulation. The trimethylsilyl group facilitates the Lewis acid catalyzed allylation of an aldehyde or acetal while the phenylthio group directs a 6-endo-trig radical cyclization reaction.

Aldehydes, RCHO (R = Me, Et, iPr, and c-C6H11) have been converted via alkylation, cyclopropanation, oxidation, condensation with p-tosylhydrazine, reduction and perhydrolysis into 2-hydroperoxyalkylcyclopropanes RCH(OOH)CH2c-C3H5, and thence by cycloperoxymercuriation and reductive demercuriation into the corresponding 3-alkyl-5-ethyl-1,2-dioxolanes.

The irradiation of alkyl 4-nitrobenzenesulfenates with >300-nm wavelength light in benzene solution results in the homolytic cleavage of the O-S bond.The tertiary alkoxy radicals thus formed undergo β scission to produce carbon-centered free radicals in e

Hydroboration of (+)-2-carene, readily available via the base-induced isomerization of (+)-3-carene, provides bis(2-isocaranyl)borane, which can be readily transformed into B-allylbis(2-isocaranyl)borane (2-dICr2BAll). This new reagent undergoes asymmetric allylboration with a variety of aldehydes and affords the corresponding homoallylic alcohols in 94-99% ee. The enantioselectivities realized with this reagent are significantly higher than those realized with the previously explored reagents, B-allyldiisopinocampheylborane (dIpc2Ball) and B-allylbis(4-isocaranyl)borane (4-dIcr2BAll).

Aldehydes and ketones of the general formula I STR1 where R1 is hydrogen or an organic radical of 1 to n carbon atoms and R2 is a non-aromatic organic radical of 1 to m carbon atoms, (m+n) ranging from 2 to 24 and R1 and R2 being combinable to form a 4- to 12-membered ring, are prepared in a continuous manner by oxidizing an alcohol of the general formula II STR2 with oxygen or an oxygen-containing gas at elevated temperatures in the gas phase in the presence of a catalyst, by effecting the oxidation by means of a supported catalyst composed of an inert carrier having a smooth surface and from 0.1 to 20% by weight, based on the amount of carrier, of an active layer of copper, silver and/or gold in a tubular reactor or tube bundle reactor where the internal diameter D of the tube or tubes ranges from 10 to 50 mm and the largest diameter d of the coated supported catalysts is subject to the relationship d=from 0.1 to 0.2 D.