摘要:

AbstractThe sulfinates (E)‐R1‐C≡C‐C(R2, CH=CHR3)‐OS(O)Me (1) have been treated with [R4CuBr]MgX·LiBr (4) in tetrahydrofuran. The ratio allylicversuspropargylic 1,3‐substitution in1, leading to R1‐C≡C‐CR2=CH‐CHR3R4(2,Z/E≥ 86/14) and (E)‐R1R4C=C=CR2‐CH=CHR3(3) respectively, depends on the size of the substituents R1and R3. As could be concluded from the reaction of (E)‐1(R1=R2=H, R3= ‐CH(OEt)2) and of the corresponding methanesulfonate (E)‐5with the heterocuprate [n‐C8H17CuBr]MgBr·LiBr, the ratio2/3is also influenced by the nature of the leaving group. A very high regioselectivity has been found if (E)‐5was reacted with the homocuprate (n‐C8H17)2CuMgBr·LiBr instead of the heterocuprate. The latter reaction is part of an attractive route to the presumed sex attractant of the Male Dri

ISSN:0165-0513    

DOI:10.1002/recl.19790980202

出版商:WILEY‐VCH Verlag    

年代:1979

数据来源: WILEY

摘要:

AbstractThe synthesis and cationic cyclization of 2‐[6‐(3‐methoxyphenyl)‐2‐methyl‐(E)‐3‐hexenyl]‐3‐methyl‐2‐cyclopentenol (12) was investigated. The major cyclization products were 1‐ and 3‐methoxy‐11α,17‐dimethyl‐1,3,5(10),13(17)‐gonatetraene (14aand15a) indicating a high degree of asymmetric induction by the pro‐C(11) chiral centre. Compound15awas converted into

ISSN:0165-0513    

DOI:10.1002/recl.19790980203

出版商:WILEY‐VCH Verlag    

年代:1979

数据来源: WILEY

摘要:

AbstractCarbonyl compounds, activated by electron‐withdrawing groups, add to 1,1‐dimethoxybutadiene (Ia), yielding 2,2‐dimethoxy‐5,6‐dihydropyrans (IIa). 1,1,4‐Trimethoxybutadiene (Ib) reacts in a similar way with suitably activated ketones, but gives[2 + 2]‐cycloadditions with activated aldehydes. The different behaviour is ascribed to steric factors. Acid hydrolysis of the 2,2‐dimethoxydihydropyrans yields α,β‐unsaturated esters and corresponding lactones, or dienyl esters depending on the reaction conditions used.1,1‐Dimethoxy‐3‐(trimethylsilyloxy)butadiene (Ic) yields Diels‐Alder adducts even with non‐activated carbonyl compounds, when zinc chloride is used as a catalyst. The products can be converted into dihydro‐γ‐pyrones by treatment w

ISSN:0165-0513    

DOI:10.1002/recl.19790980204

出版商:WILEY‐VCH Verlag    

年代:1979

数据来源: WILEY

摘要:

AbstractGermylated 3‐, 4‐ or 5‐membered heterocycles containing a Ge‐N bond are synthetized by direct aminolysis (followed by dehydrochlorination) or by action of amino dilithium compounds on germylated dichlorides of the general structure. The preparations of these new dichlorides are also described.2‐Germaazolidines are thermally stable. 2‐Germaazétidines decompose at moderate temperature, through a β‐elimination process, to give germa‐imineand alkene. 2‐Germaaziridines, likely in equilibrium with an open zwitter ionic form, readily decompose through an α‐elimination process, to lead to the corresponding germylene and imine.The reactivity of these heterocycles has been considered from specific reactions of the Ge‐N bond: cleavage by protic species, LiAlH4reduction or addition on insaturated compounds (CS2, PhNCO), the last reaction l

ISSN:0165-0513    

DOI:10.1002/recl.19790980205

出版商:WILEY‐VCH Verlag    

年代:1979

数据来源: WILEY

摘要:

AbstractThe sesquiterpenoid 3β‐acetoxy‐2β‐hydroxy‐thujopsane forms orthorhombic crystals of space groupP212121with cell dimensionsa= 7.547,b= 14.167,c= 14.783 Å andZ= 4. The cyclohexane ring carrying the cyclopropane ring is approximately in a half chair conformation and the other ring is a slightly deformed chair. Two bonds of the cyclopropane ring are shortened (to 1.490 and 1.492 Å) and one is lengthened (to 1.534 Å), an uncommon phenomenon, which is assumed to be correlated with the position of the hydroxyl‐oxygen atom with respect to the cyc

ISSN:0165-0513    

DOI:10.1002/recl.19790980206

出版商:WILEY‐VCH Verlag    

年代:1979

数据来源: WILEY

摘要:

AbstractLithium 1‐alkynethiolates and ‐selenolates RC≡CXLi (X = S, Se) have been converted with allyl bromide and with 1‐bromo‐2‐butyne into the compounds H2C=CH‐CH2‐X‐C≡C‐R and CH3C≡C‐CH2‐XC≡C‐R (R =t‐C4H9, Me3Si; X = S, Se), respectively. Upon heating, only the sulfides H2C=CH‐CH2‐S‐C≡C‐R gave isolable thioketenes by [3,3]‐sigmatropic rearrangement. The analogous selenoketene and the thioketene from the rearrangement of Me3Si‐C≡C‐X‐CH2CCH3are unstable.In the reaction of CH3C≡C‐SeSiMe3andt‐C4H9C≡C‐SeSiMe3with diethylamine, giving the selenoamides C2H5C(Se)NEt2andt‐C4H9CH2C(Se)NEt2, the selenoketenes CH3CH=C=Se andt‐C4H9CH=C=Se are the presumed intermediates. Pure bis(trimethylsilyl)selenoketene [Me3Si]2C=C=Se (7) was obtained in 80% yield

ISSN:0165-0513    

DOI:10.1002/recl.19790980207

出版商:WILEY‐VCH Verlag    

年代:1979

数据来源: WILEY

ISSN:0165-0513    

DOI:10.1002/recl.19790980208

出版商:WILEY‐VCH Verlag    

年代:1979

数据来源: WILEY

ISSN:0165-0513    

DOI:10.1002/recl.19790980201

出版商:WILEY‐VCH Verlag    

年代:1979

数据来源: WILEY