Insect pheromones - syntheses of chiral and achiral components of the sex pheromones of dermestid beetles of the genus Trogoderma

(+)(S)(Z)-14-methyl-8-hexadecen-1-ol (I) was prepd. from (+)(S)-EtCHMeCH2CH2CH:CH2 (II) in a series of reactions.  Thus, II was subjected to hydroboration-bromination, coupled with HC≡CLi, and lithiated, coupled with 7-iodo-1-heptyl 2-tetrahydropyranyl ether, and hydrolyzed to give (+)(S)-EtCHMe(CH2)4C≡C(CH2)7OH (III); the selective hydrogenation of III gave I.  1-Decyne was converted to (Z)-Me(CH2)7CH:CH(CH2)5CO2Me by lithiation, coupling with 6-iodo-1-hexyl 2-tetrahydropyranyl ether, hydrolysis, selective hydrogenation, oxidn., and esterification by CH2N2

Convenient copper- and solvent-free Sonogashira-type alkynilation of aryl iodides and bromides using Pd EncatTM

A straightforward methodology is described for the copper- and solvent-free alkynylations of aryl iodides and bromides using 0.1–0.01 mol % of Pd as Pd EnCatTM 40 or TPP30. High yielding reactions can be achieved under aerobic conditions for a variety of activated and deactivated aryl iodides; a few examples with aryl bromides are also described. Microwave irradiation is able to enhance yields and rates of these reactions

Stereospecific synthesis of (Z)-13-hexadecen-11-yn-1-yl acetate. The sex pheromone of the processionary moth, and of (5Z,7E)-5,7-dodecadien-1-ol, a sex pheromone component of the forest tent caterpillar

(Z)-13-hexadecen-11-yn-1-yl acetate (2), the sex pheromone of Thaumetopoea pytyocampa, and (5Z,7E)-5,7-dodecadien-1-ol (3), a sex pheromone component of Malacosoma disstria, have been prepared in high chemical and stereoisomeric purity by synthetic schemes involving the stereospeific coupling of ω-functionalized 1-alkynes with (Z)- or (E)-1-iodo-1-alkenes in the presence of a catalytic amount of (PPh3)4Pd and Cul, under phase transfer conditions

Preparation of arylzinc halides by silver promoted oxidative metalation

Organozinc halides are useful reagents for organic synthesis, as witnessed by their wide use as nucleophiles in the Negishi coupling, a powerful and versatile reaction for carbon-carbon bond formation. Direct insertion of zinc metal into organic halides provides the most practical and atom-economical way for preparing these organometallic reagents. Nevertheless, oxidative metalation often has limited application due to long reaction times required by many substrates. We found that a catalytic amount of silver acetate efficiently promotes direct insertion of zinc metal to aryl iodides, having different structure, in ethereal solvent. Also electron-rich substrates rapidly undergo oxidative metalation. Arylzinc iodides thus formed give Negishi coupling products under mild reaction conditions. In all cases, reaction times required to provide full conversion in the metalation step are between 2 and 15 hours even on electron-rich substrates, which are scarcely reactive under the most commonly used reaction conditions

Synthesis of the propionates of (2R,8R)- and (2RS,8R)-8-methyl-2-decanol, the attractants of the western corn rootworm

(2R,8R)-8-Methyl-2-decanoyl propionate has been prepd. from enantiomerically pure (R)-HuO2CCH2CHMeCH2CO2Me, and (S)-glutamic acid, as chiral precursors.  These have been stereospecifically converted into (R)-EtCHMeCH2Br, and (R)-1,4-pentanediol, resp.  Biol. active (2RS)-8R)-EtCHMe(CH2)5CHuMeO2CL was prepd. from (R)-CH2CH2Br and racemic HOCHMe(CH2)3OH

Synthesis of 1-acetoxy-2-alkyl-2,3-butadienes and/or 2,3-dialkyl-1,3-butadienes from 1,4-diacetoxy-2-butyne and alkyl heterocuprates

AcOCH2C≡CCH2OAc (I) reacts with RCu.MgBrCl.LiBr [II, R = Pr, Me(CH2)4, (S)-EtMeCHCH2], prepd. by reaction of RMgCl with CuBr and LiBr, to form allenes CH2:C:CRCH2OAc (III) and butadienes H2C:CRCR:CH2, in yields depending on the I:II ratio.  III react with other II to give unsym. butadienes.  Mechanisms are proposed to account for the products

Selective synthesis of (S)-1-methylbutyl (E)-2,4-dimethyl-2-pentanoate, and aggregation pheromone component of Rhyzopertha dominica, and of (E)-2-butyl-2-octenal, an alarm pheromone component of Oecophylla longinoda, via 2-substituted 1-silyl-1-stannylethenes

Two easily available stereodefined organobimetallic compounds, i.e. (Z)-1-trimethylsilyl-1-trimethylstannyl-3-methyl-1-butene, (Z)-1a, and (Z)-1-trimethylsilyl-1-tributylstannyl-1-heptene, (Z)-12, which serve as direct precursors to reagents which are synthetic equivalents of the 1-alkene 2d1 synthon 20, have been used as key intermediates in selective and efficient syntheses of two insect pheromone components, i.e. enantiomerically pure (S)-1-methylbutyl (E)-2,4-dimethyl-2-pentenoate (dominicalure-2), (S)(E)-10, and (E)-2-butyl-2-octenal, (E)-11, respectively