The temperature dependence of intramolecular [2 + 2] photocycloadditions has been studied for two series of cyclohexenones, α- and β-linked, respectively, to a variously substituted olefin moiety via a trimethylene chain. With one exception, the disappearance quantum yield of the starting material decreases sharply in a narrow temperature range to approximately one-half of its initial value. No such sharp temperature effect was observed on the product ratio, which either remains constant or varies monotonically over the entire temperature range. This indicates that the temperature effects on the disappearance rate and on the product distribution refer to two distinct processes. A mechanism rationalizing this behavior is proposed.

Complete trapping of 1,4-diradical intermediates, formed in the intramolecular [2+2] photocyclo-addition of 13, provide direct evidence for the exclusive formation of the first bond at the C(β) of the cyclic enone. This result is found in full agreement with the previously studied compounds 1.

Separation and structure determination of the previously trapped products 5 is described, the results present the first experimental evidence for the ''twisted'' approach. An important temperature effect was found.

The influence of substituents on the regio- and stereochemistry of the intramolecular [2+2] photocycloaddition of compound 1–8 has been studied. All photoadducts are formed via parallel approach and syn-addition. The endo/exo ratio was used as indicator for the structure of the diradical intermediates.

The effect of substituents on the mode of approach and the endo/exo ratio in intramolecular [2+2] photocycloaddition reactions were studied.

The 1,2,4,6-Tetra-O-pivaloyl-D-gluco-pyranose 3 and 1,2,3,6-Tetra-O-pivaloyl-D-gluco-pyranose 4 have been prepared in one step from anhydrous glucose and pivaloyl chloride. These new intermediates can be converted into the corresponding esters, or used in the synthesis of a disaccharide in good yield. Thus, 2,3,6-Tri-O-pivaloyl-gluco-pyranose 10 can be prepared from 4, and used for preparation of β-gluco derivatives via the corresponding trichloroacetimidate 12.

Products formed on irradiation of substituted cyclohexenones 1 and 6 have provided information on the structure of the diradical intermediates involved in [2+2] photocycloaddition. It was found that compound 11 cannot be used for studying the structure of diradicals intermediates in intermolecular [2+2] photocycloaddition.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Two-year-old trees of cultivar ‘Rangpur’ lime (Citrus limonia Osb.) and of cultivar ‘Oroblanco’, a triploid pummelo-grapefruit hybrid (Citrus grandis Osb. × Citrus paradisi Macf.), which had not reached flowering stage, were grown under greenhouse conditions. Cuttings from the last vigorous vegetative flush were taken from each species for rooting experiments. Callus formation and percentage of rooting were determined after 19 and 36 days. Endogenous indole-3-acetic acid (IAA) content and avocado rooting promoter (ARP)-like activity were determined in leaves and bark (cortex) of the lower end of the cutting on day of excision and 19 days later. Rooting of the easy-to-root ‘Rangpur’ lime reached 77% after 19 days and 100% after 36 days. At those times the difficult-to-root ‘Oroblanco’ did not root at all or reached 12% rooting, respectively. At Day 19 the level of free IAA in the bark of ‘Rangpur’ lime was 3.5 times higher than that at Day 0, and 3.6 times higher than in the ‘Oroblanco’ bark on the same day. ARP was found in both species at excision day and after 19 days using gas-chromatography analysis. The ARP activity on the day of excision was only slightly higher in the leaves and bark of ‘Rangpur’ lime than in ‘Oroblanco’, but after 19 days ARP-like activity rose approximately 45% in the basal bark of ‘Rangpur’ lime with no such increase in its leaves or in the leaves and bark of ‘Oroblanco’. The differences in IAA level and ARP-like activity in the two citrus cultivars appear to be correlated with their ease of rooting, but it is not possible to tell whether the increase in IAA and ARP over the rooting period is the cause or result of root initiation.

(Z,Z)-6,9-cis-(3S,4R)-Epoxynonadecadiene 9a and (Z,Z,Z)-3,6,9-nonadecatriene have been identified as sex pheromone components in female ovipositor extracts and effluvia of the geometrid Boarmia selenaria. The identification was based on relative retention times on gas chromatographic columns, GC-MS, chemical enantioselective syntheses, EAG, wind-tunnel behavioral experiments, and field tests. A single female ovipositor extract contained an average of 42 ng of (Z,Z)-6,9-cis-3,4-epoxynonadecadiene and 2 ng of (Z,Z,Z)-3,6,9-nonadecatriene. EAG, wind-tunnel behavioral studies, and field tests demonstrated that male B. selenaria exhibit preferential attraction for the (3S,4R)-enantiomer of (Z,Z)-6,9-cis-3,4-epoxynonadecadiene. Only in effluvia and ovipositor extracts of calling females was (Z,Z)-6,9-cis-3,4-epoxynonadecadiene detected, whereas relatively high amounts of (Z,Z,Z)-3,6,9-nonadecatriene were found in noncalling females. Wind-tunnel behavioral studies showed that (Z,Z,Z)-3,6,9-nonadecatriene did not elicit any response in the males, and when tested in combination with a mixture of monoepoxynonadecadienes, (Z,Z,Z)-3,6,9-nonadecatriene decreased the observed behavioral responses. A possible precursor role for (Z,Z,Z)-3,6,9-nonadecatriene in the pheromonal system is discussed.

Methods are described by means of case studies for ascertaining the orientation of substituents in naphthalene, in particular in products derived from naphthalenesulphonic acid derivatives, by means of a combination of modern 1H NMR methods.

A qualitative analytical method for avocado rooting promoters (ARP) has been developed based on gas chromatography (GC) of silylated samples.Leaves of easy and difficult to root clones of Laurus nobilis L. and Magnifera indica L. were extracted and analyzed for ARP components and for ARP-like activity. Avocado rooting promoter compounds 1I and/or 2I can be detected in leaf extracts of both easy and difficult to root bay laurel. It was found that ARP-like activity was higher in the easy to root than in the difficult to root plants as manifested in the mung bean rooting bioassay. Compounds 1I and/or 2I were found in the easy to root mango clone but not in the difficult to root one. However, ARP-like activity was similar in the two extracts.

It was found that in [2+2] intramolecular photocycloaddition the isomer rationin system II is different from system I. Compounds 1 and 20 cyclize with high stereoselectivity to give in high yield 3 and 21 respectively. The mechanistic consequences are discussed.

16-Heptadecyn-1,2,4-triol is the most active component of the avocado rooting promoter (ARP). All four diastereoisomers of this compound have been synthesized. Their root promoting activity was determined over the physiologically active concentration range. It was found that the (2R,4R)-stereoisomer exerts a rooting activity similar to that of the extracted and purified compound from avocado tissues. The (2R,4S), and (2S,4R)-stereoisomers had lower activity and the (2S,4S)-stereoisomer had the lowest activity. It is concluded that the natural form, (2R,4R), acts in the rooting process either in its original structure or after reaction which does not alter its chiral centres.

(Z,Z)-6,9-cis-3S,4R-Epoxynonadecadiene has been identified as the major sex pheromone component of the Geometrid Boarmia selenaria. A short and efficient synthesis of the chiral methylene-interrupted diene-epoxide has been developed for both enantiomers.

ChemInformVolume 20, Issue 52 Preparative Organic Chemistry ChemInform Abstract: Trapping of 1,4-Diradical Intermediate in Intramolecular (2 + 2)Photocycloaddition. D. BECKER, D. BECKER Dep. Chem., Technion-Israel Inst. Technol., Technion City, Haifa 32000, IsraelSearch for more papers by this authorN. HADDAD, N. HADDAD Dep. Chem., Technion-Israel Inst. Technol., Technion City, Haifa 32000, IsraelSearch for more papers by this authorY. SAHALI, Y. SAHALI Dep. Chem., Technion-Israel Inst. Technol., Technion City, Haifa 32000, IsraelSearch for more papers by this author D. BECKER, D. BECKER Dep. Chem., Technion-Israel Inst. Technol., Technion City, Haifa 32000, IsraelSearch for more papers by this authorN. HADDAD, N. HADDAD Dep. Chem., Technion-Israel Inst. Technol., Technion City, Haifa 32000, IsraelSearch for more papers by this authorY. SAHALI, Y. SAHALI Dep. Chem., Technion-Israel Inst. Technol., Technion City, Haifa 32000, IsraelSearch for more papers by this author First published: December 26, 1989 https://doi.org/10.1002/chin.198952062Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume20, Issue52December 26, 1989 RelatedInformation

For the first time a 1,4-diradical intermediate 10 was trapped in 43% yield in an intramolecular [2+2] photocycloaddition of olefins to cyclohexenone. The results support the assumption that the first bond is formed to carbon-β of the enone system.

AbstractThe mechanism of intramolecular [2 + 2] photocycloaddition of 1b has been investigated. Structure determination of deuterium‐labeled photoadducts was accomplished by 2H NMR.

The effects of 21 days of haloperidol treatment on central benzodiazepine (BZ) receptors in the cerebral cortex of rats and on peripheral-type BZ binding sites (PBS) in the cerebral cortex and heart of rats were studied. Neuroleptic treatment did not affect the maximal binding capacity or the affinity of the central BZ receptor to 3H-flunitrazepam. Chronic haloperidol treatment resulted in a significant increase of 38% in PBS density in the cerebral cortex, with no alteration in PBS density in the heart. No alteration in PBS affinity for its ligand 3H-PK 11195 was observed, either in the cerebral cortex or in the heart. The modulatory effect of chronic haloperidol administration on PBS density in the brain may be related to some of the neurobehavioral or hormonal effects of the drug.

The target molecules 1 and 2 were synthesized from a common intermediate 6 prepared from (R)-Limonene. The first enantioselective synthesis of 2 is described.