1,4-Butanediones

British investigators (Haddow and Timmis 1951) synthesized and studied esters of the methanesulfonic acid. The most active derivative was the dimethylsulfonic ester of 1,4-butanedione, known as busulfan. Busulfan interacts with the thiol groups of proteins and amino acids some of its metabolites can alkylate the thiols of cysteine, peptides and proteins. Busulfan exerts selective cytotoxic activity in hematopoietic bone marrow cells and inhibits the formation of granulocytes and platelets. It slightly affects the lymphoid tissue. 

A limited number of hypervalent iodine-mediated synthesis of thiophenes and benzothiophenes have been reported. An indirect approach for the synthesis of thiophenes involves formation of 1,4-butanediones [85JC-S(CC)420 87JCS(P1)559 88TL3703 89JOC2605], followed by treatment with phosphorus pentasulfide. This approach is especially useful for the synthesis of 3,2 5, 3"-terthiophene (134) starting from 1,4-diketone 65 (85SC789). 

The furans (15 R1, R2 = H, Me or Ph) are obtained by thermolysis of the cyclobutenediols (14) intermediate 1,4-diketones were isolated in two cases (77S280). It has been shown that gas-phase proton catalyzed dehydration of both 2,5-hexanedione (16 R=Me) and 1,4-diphenyl-1,4-butanedione (16 R=Ph) yields protonated 2,5-disubstituted furans (17) (80T929). 

Reduction of the semicarbazone of a phenacyl bromide in dimethylformamide (DMF) yields the bis-semicarbazone of 1,4-diaryl-1,4-butanedione, which in DMF forms 3,6-diarylpyridazine [4] or, after treatment with aqueous acid, 2,5-diary 1-furan [5], Reduction of phenacyl bromide in DMF is reported to give 2,4-diarylfuran [6]. 

The reaction of the trimethylsilyl enol ether of various acetophenone derivatives (122) with the electrophilic PhIO-HBF4 at - 78 C generated a highly reactive iodonium salt, an a-ketomethyl phenyliodonium salt (123). Treatment of this salt with a second different trimethylsilyl enol ether (124) led to unsymmetrical 1,4-butanediones (125), as major products.232,233 (Scheme 5.12)... 

Fig. 6 Comparison of weight loss and the amoimt of monomeric hydrolysis products, i.e. 1,4-butanedion and succinic acid, resulting from the hydrolysis of poly(butylene succinate) shows further hydrolysis of oligomeric hydrolysis products. Reprinted from [131] with permission of Elsevier. Elsevier (2004)...

PAAL-KNORR Pyrrole Synthesis Pyrrole synthesis from 1,4-butanediones and amines (see 1st edition)... 

Diphenyl-1,4-butanedione Diphenyl sulfide Diphenyl sulfone Diphenyl sulfoxide... 

The method could be applied to reduce 1,3-diaryl-1,3-diketones to 1,3-diaryl-1,3-propanediols in 93-100% yields and high ee s (>97% ee). The products were obtained as a mixture of diastereomers (81 19 - 90 10) and could be purified by recrystallization.Symmetrical 2-substituted-l,3-diaryl-1,3-diketones underwent reductive desymmetrization to give rise to /8-hydroxyketones (45-97% yields) in high ee s (>91% ee) and diastereoselectivities (dr>99 l) (eq 32). Unsymmetrical 2-alky 1-3-ary 1-1,3-diketones were reduced chemoselectively at the aryl-substituted carbonyl group to yield 2-alkyl-3-aryl-3-hydroxyketones (41-48% yields) in high ee s (>95%) and diastereoselectivities (( >97 3). The yields could be further improved by the addition of a stoichiometric amount of sodium methoxide in a one-pot reaction. 1,4-Diaryl-1,4-butanediones were reduced to enantiopure l,4-diaryl-l,4-butanediols (60-100% yields), which... 

Six aromatic oligo-guanylhydrazones (Ar,AT -bis[3,5-diacetyl]decanetetrakis-, 2,6-diacetylaniline-, 1,4-diphenyl-1,4-butanedione-bis-, Af,Af -bis[3,5-diacetyl-... 

We have synthesized such a precursor polymer by using the Stetter reaction (scheme 2). Poly-1,4-phenylene-1, 4 -butanedione 9 was formed in the reaction of terephthalic-dicarboxaldehyde 10 and the bis-Mannich base of 1,4-diaeetylbenzene 11 in a yield of 81%. The conversion of 9 into the alternating copolymers of p -phenylene-2,5-pyrrole 12 and p-phenylene-2,5-thiophene 13 is performed with liquid NH3 and Lawesson s reagent, respectively (scheme 3). Upon doping with either Ig or AsFg both polymers 12 and 13 become electrically conducting with specific conductivities up to 0.1 S/cm. 

However, a 1,4-dithione might also be formed upon addition of a second equivalent of H2S onto one adjacent triple bond. In the laboratory, the reaction of a 1,4-butanedione with H2S is a standard method of synthesis of thiophenes. It has not been tested as a pathway for the conversion of diacetylenes into thiophenes or as a more direct alternative to 1,3-butadiynes in the biosynthesis of thiophenes. 

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