A mild Cu(I)-catalyzed regioselective diamination of conjugated dienes

This paper describes a novel diamination process that uses CuCl as catalyst and di-tert-butyldiaziridinone as nitrogen source. A wide variety of conjugated dienes and a triene can be effectively diaminated in good yields with generally high regioselectivity under mild reaction conditions.     

Efficient method to locate double bond positions in conjugated trienes

The double bond positions of 11 conjugated trienes were unambiguously located through a simple derivatization method amenable to nanogram-scale analyses. The trienes were reacted with the powerful dienophile 4-methyl-1,2,4-triazoline-3,5-dione (MTAD), and the mass spectra of the resulting cycloadducts exhibited large diagnostic fragments which allowed the unequivocal location of the double bonds in the parent triene in most cases. Catalytic hydrogenation of the cycloadducts produced saturated compounds with characteristic mass spectral fragments from which the positions of the trienes in the parent compounds could be readily confirmed. Application of the method was demonstrated by the microscale identification of two conjugated triene and one conjugated diene components from extracts of the sex pheromone gland of the saturniid moth Automeris cecrops pamina.     

Geometric effects in the excited states of conjugated trienes

The fluorescence spectra and intrinsic lifetimes of two constrained trienes [cholesta-4,6,8(14)-triene and cholesta-5,7,9(11)-triene-3β-01] indicate that the lowest energy singlet—singlet transition of the s-trans,cis,s-trans 4,6,8(14) triene is a weak transition to a ¹A_g-like excited state while the s-cis,trans,s-cis 5,7,9(11) triene has a lowest transition which is strongly allowed to a ¹B_u-like excited state.     

An organocatalyzed highly regioselective one-pot approach to the synthesis of tetrahydrobenzofuranones

An organocatalyzed highly regioselective synthesis of substituted tetrahydrobenzofuran-4-ones based on the ring opening followed by cyclization of epoxides with enamines of 1,3-cyclohexanediones in a domino fashion is described. It is a high yielding (74–93%) synthetic protocol tolerant to a wide range of substrates. Ambient temperature, organocatalytic approach, atom-economy, and formation of water as the only by-product are some of the attractive features of the present methodology.     

Stereoselective synthesis of unsymmetrical conjugated dienes and trienes utilizing silacyclobutenes

Treatment of the different kinds of alkynyl-substituted dialkynyldiarylsilanes with zirconocene-ethylene complex Cp₂Zr(CH₂CH₂) followed by acidification with 3 N HCl gave regio- and stereoselectively the corresponding silacyclobutenes in good yields. Desilylation of the silacyclobutenes with tetrabutylammonium fluoride afforded stereoselectively unsymmetrical conjugated (1E,3E)-dienes and -trienes (R¹ or R² = 1-cyclohexenyl) in excellent yields.     

Gold(I)-catalysed synthesis of conjugated trienes

Gold(I)-catalysed reaction between cyclopropenes and furans produces functionalised conjugated trienes. The reaction is mild, facile and proceeds with very low catalyst loadings.     

The regioselective deprotonation of conjugated esters

A stereospecific synthesis of the E and Z esters of C–4 deuterated 3-methyl-2-butenoic acid from methyl acetoacetate is reported; the labelled methyl 3-methyl-2-butenote is regioselectively deprotonated syn to the ester group under kinetic conditions.     

Cu(I)-catalyzed asymmetric diamination of conjugated dienes

A Cu(I)-catalyzed asymmetric diamination for a variety of conjugated dienes and a triene with encouraging ee's has been effectively achieved using (R)-DTBM-SEGPHOS as a chiral ligand and di- tert-butyldiaziridinone as the nitrogen source.     

Telomerization of conjugated dienes and trienes with pyrazolines catalyzed by palladium complexes

Conclusions The telomerization of pyrazolines with 1,3-dienes and trienes in the presence of homogeneous Pd catalysts results in the synthesis of the corresponding N-2,7-octadienyl derivatives of heterocyclic amines.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 652–655, March, 1980.     

The regioselective deprotonation of conjugated acids

A stereoselective synthesis of E and Z C-4 deuterated 3-methyl-2-butenoic acid from methyl acetoacetate is described; the labelled acids are regioselectively deprotonated s$\text{y}$n to the acid function under kinetic conditions.     

Palladium-catalyzed cycloisomerisation reaction of 1,6-enyne acetic esters to form five-membered nitrogenated heterocyclic conjugated trienes

A palladium-catalyzed cycloisomerisation reaction of 1,6-enyne acetic esters have been developed. This cyclization reaction shows excellent regioselectivity and good functional group tolerance to obtain five-membered nitrogenated heterocyclic conjugated trienes in moderate to excellent yields. The resulting conjugated trienes could be facilely converted to highly substituted benzenes through Diels-Alder reactions.     

Effects of wavelength and conformation on the photochemistry of vitamin D and related conjugated trienes

Irradiation experiments under various conditions establish that the photoreactions of conjugated trienes are governed by the ground state conformational equilibrium and the NEER principle, as well as by the wavelength dependent relaxation behaviour of the excited species.     

Complementary regioselectivity in the Cu(I)-catalyzed diamination of conjugated dienes to form cyclic sulfamides

This paper describes the regioselective diamination of conjugated dienes using inexpensive Cu(I) as catalyst and N,N-di-tert-butylthiadiaziridine 1,1-dioxide as nitrogen source. The regioselectivity of diamination is likely due to dual mechanistic pathways which are greatly influenced by reaction conditions and the nature of the diene. A variety of useful internal and terminal cyclic sulfamides can be obtained in good yield.     

Synthesis of conjugated trienes by palladium(0) catalysed cross coupling

2-Bromo-1-ethenyl-3,4-dihydronaphthalene (1) is subjected to palladium(0) catalysed coupling to a series of vinyl and aryl iodides via a bromozinc intermediate; the products when heated undergo 6π-electrocyclic ring closure.     

An efficient non-catalytic, regioselective approach to the synthesis of angularly fused polycyclic systems

A novel approach to the synthesis of partially reduced different ring sizes of PAH analogs with sec.amino and nitrile functionalities is delineated through base-induced ring transformation of 4-sec.amino-2-oxo-5,6-dihydro-2H-benzo[h]chromene-3-carbonitriles by a carbanion, generated in situ from cyclopentanone, cyclohexanone, cycloheptanone, and cyclooctanone separately in good yields. An increase in the size of cycloalkanone ring beyond cyclooctanone restricts the ring transformation under analogous reaction conditions possibly due to bulky conformation of higher homologs. The synthetic method provides an efficient general route for the construction of angularly fused partially reduced polycyclic aromatic hydrocarbons: 5-sec.amino-2,3,6,7-tetrahydro-1H-cyclopenta[c]phenanthrene-4-carbonitriles, 6-sec.amino-2,3,4,7,8-pentahydro-1H-benzo[c]phenanthrene-5-carbonitriles, 7-sec.amino-2,3,4,5,8,9-hexahydro-1H-cyclohepta[c]phenanthrene-6-carbonitriles, and 8-sec.amino-2,3,4,5,6,9,10-heptahydro-1H-cycloocta[c]phenanthrene-7-carbonitriles.     

Chiral N-heterocyclic carbene--Pd(0)-catalyzed asymmetric diamination of conjugated dienes and triene

Studies show that a variety of conjugated dienes and triene can be enantioselectively diaminated using di-tert-butyldiaziridinone as nitrogen source and chiral N-heterocyclic carbene-Pd(0) complex as catalyst in good enantioselectivity (62-91% ee) with high regio- and diastereoselectivity.