73617-44-4

Upstream product

• 77-79-2 3-Sulfolene 
• 100-39-0 benzyl bromide 
• 620-05-3 iodomethylbenzene 
• 1007-52-9 (E/Z)-1-benzylbuta-1,3-diene 
• 122-78-1 phenylacetaldehyde 

Downstream Products

• 105231-04-7 (1R,2S,3S)-3-Benzyl-cyclohex-4-ene-1,2-dicarboxylic acid dimethyl ester 
• 105230-98-6 C₁₈H₁₈ 
• 105230-99-7 1,4-dibenzyl-1,3-butadiene 
• 105230-94-2 (2R,5S)-2,5-Dibenzyl-2,5-dihydro-thiophene 1,1-dioxide 
• 105230-93-1 (2S,5S)-2,5-Dibenzyl-2,5-dihydro-thiophene 1,1-dioxide 

Relevant academic research and scientific papers

Substituent effect on the competition between hetero-Diels-Alder and cheletropic additions of sulfur dioxide to 1-substituted buta-1,3-dienes

The reactivity of sulfur dioxide toward variously substituted butadienes was explored in an effort to define the factors affecting the competition between the hetero-Diels-Alder and cheletropic additions. At low temperature (2 in the hetero-Diels-Alder mode in the presence of CF3COOH as promoter. In the case of (E)-1-ethylidene-2-methylidenecyclohexane ((E)-4a), the [4+2] cycloaddition of SO2 is fast at -90° without acid catalyst. (E)-1-(Acyloxy)buta-1,3-dienes (E)-1c, (E)-1y, and (E)-1z with AcO, BzO, and naphthalene-2-(carbonyloxy). substituents, respectively also undergo the hetero-Diels-Alder addition with SO2+CF3COOH at low temperatures, giving a 1:10 mixture of the corresponding cis- and trans-6-(acyloxy)sultines c-2c,y,z and t-2c,y,z, respectively). Above -50°, the sultines undergo complete cycloreversion to the corresponding dienes and SO2, which that add in the cheletropic mode at higher temperature to give the corresponding 2-substituted sulfolenes (=2,5-dihydrothiophene 1,1-dioxides) 3. The hetero-Diels-Alder additions of SO2 follow the Alder endo rule, giving first the 6-substituted cis-sultines that equilibrate then with the more stable trans-isomers. This statement is based on the assumption that the S=O group in the sultine prefers a pseudo-axial rather than a pseudo-equatorial position, as predicted by quantum calculations. The most striking observation is that electron-rich dienes such as 1-cyclopropyl-, 1-phenyl-, 1-(4-methoxyphenyl)-, 1-(trimethylsilyl)-, 1-phenoxy-, 1-(4-chlorophenoxy)-, 1-(4-methoxyphenoxy)-, 1-(4-nitrophenoxy)-, 1-(naphthalen-2-yloxy)-, 1-(methylthio)-, 1-(phenylthio)-, 1-[(4-chlorophenyl)thio]-, 1-[(4-methoxyphenyl)thio]-, 1-[(4-nitrophenyl)thio]-, and 1-(phenylseleno)buta-1,3-diene, as well as 1-(methoxymethylidene)-2-methylidenecyclohexane (4f) do not equilibrate with the corresponding sultines between -100 and -10°, in the presence of a large excess of SO2, with or without acidic promoter. The hetero-Diels-Alder additions of SO2 to 1-substituted (E)-buta-1,3-dienes are highly regioselective, giving exclusively the corresponding 6-substituted sultines. The 1-substituted (Z)-buta-1,3-dienes do not undergo the hetero-Diels-Alder additions with sulfur dioxide.

Stereoselective Synthesis of (E)-, (E,Z)-, and (E,E)-Conjugated Dienes via Alkylation of 3-Sulfolenes as the Key Step

A new stereoselective method is presented for synthesizing (E)-, (E,Z)-, and (E,E)-conjugated dienes via alkylation of 3-sulfolenes as the key step.Direct alkylation of 3-sulfolene at the 2-position proceeds with good yields when labile sulfolene α-carbanion is generated in the presence of alkyl iodides in THF-HMPA solution at -78 deg C.Alkylation of 2-alkyl-3-sulfolenes gives trans-2,5-dialkyl-3-sulfolenes with 100percent regioselectivity and more than 90percent stereoselectivity.Desulfonylation of trans-3,5-disubstituted 3-sulfolenes is examined in detail, and the conditions to give stereoselectively the corresponding (E,Z)-and (E,E)-conjugated dienes are found.Applying the method, three insect pheromones, (E)-9,11-dodecadien-1-yl acetate, a sex pheromone of the red bollworm moth, (E,E)-8,10-dodecadien-1-ol, a sex pheromone of the codling moth, and (E,E)-11,13-hexadecadienal, a sex pheromone of the cabbage webworm, are easily synthesized by starting with 3-sulfolene with nearly 100percent stereoselectivity.Synthesis of cis-3,4,5-trisubstituted cyclohexenes using 2-substituted 3-sulfolenes as the diene synthons is also described.

STEREOSELECTIVE SYNTHESIS OF (E)-, (E,Z)- AND (E,E)-CONJUGATED DIENES VIA ALKYLATION OF 3-SULFOLENES AS KEY STEP

Stereoselective method for synthesizing (E)-, (E,Z)- and (E,E)-conjugated dienes via alkylation of 3-sulfolenes as key step is developed.Sex pheromones with (E)- and (E,E)-conjugated diene structures are synthesized with exclusively high stereoselectivity by applying the method.