3-Methyl-2-Butenal

Biographical Sketches

Claiton Pires Ventura was born in Minas Gerais, Brazil in 1978. He received his B.Sc. degree in pharmacy from the Universidade ­Federal de Minas Gerais in 2001 and his M.Sc. in pharmacy from the same university in 2003. He is currently working toward his Ph.D. under the supervision of Professor Rosemeire Brondi Alves. His research interests focus on the synthesis of pterocarpans from 2H-chromenes.

Introduction

3-Methyl-2-butenal, also known as 3,3-dimethylacrolein, is a very interesting reagent used in addition and cyclo­addition reactions. This colorless, light-yellowish liquid has a pungent odor and is miscible in common organic solvents and water. It is commercially available, but it can also be prepared by oxidation of 3-methyl-2-butenol with H₂O₂. Kon et al. have reported this reaction with a yield of 91%. [¹]

3-Methyl-2-butenal is an α,β-unsaturated carbonyl compound. This compound has interesting properties that result from the conjugation of the carbon-carbon double bond with the carbonyl group and the two electrophilic sites: The carbonyl carbon and the carbon atom that is in β-position to it. The polarization of electron density makes their β-carbon atoms rather electrophilic. [²]

Various examples of the use of 3-methyl-2-butenal are found in the literature. This reagent has been explored for the preparation of 1,4-dihydropiridines, [³] diene adducts, [4] pyranonaphthoquinones, [5] nitropentanal pyrrole, [6] cyclization precursors, [7] and 2H-chromenes. [9]

Abstracts

(A) Moreau et al. reported on the addition of β-enaminoacrylates to α,β-unsaturated aldehydes catalyzed by a metal-free Brønsted acid, which provides 1,4-dihydropyridines. The substituted dihydro­pyridines were obtained in moderate to good yields under mild conditions. [³]
(B) Hong et al. studied a series of homologous unsaturated aldehydes which were then reacted with l-proline in acetonitrile to afford the corresponding adducts. The reaction of 3-methyl-2-butenal with l-proline afforded a diene adduct in 82% yield via formal [4+2] cycloaddition. [4]
(C) The reaction of some naphthoquinones, α,β-unsaturated aldehyde, and β-alanine affords pyranonaphthoquinones via one-pot 6π-electrocyclization in modest to good yields (52-77%). These substances are potential carcinogenesis inhibitors. [5]
(D) The Michael addition of N-p-tosyl nitroethylpyrrole with 3-methyl-2-butenal in the presence of CsF gave the nitropentanal pyrrole, an important intermediate in the synthesis of hydrodipyrrins, in 69% yield. [6]
(E) The condensation of 3-methyl-2-butenal with p-methoxybenzyl­amine followed by triethylamine-mediated acylation with 2-bromo-2-methylpropionyl bromide produced an important cyclization precursor. [7]
(G) Ko et al. reported on cerium ammonium nitrate (CAN) and ­iodine-catalyzed reactions of indole or 1-methylindole with α,β-unsaturated ketone or aldehyde. The reaction of 3-methyl-2-butenal with indole shows different results when CAN and iodine were used as catalysts. [8]
(H) Chauder et al. reported an important condensation of phenols with 3-methyl-2-butenal in the presence of phenylboronic acid in an acetic acid/toluene solution that leads to substituted and condensed 2H-chromenes. This work constitutes a mild and advantageous complement to classical routes for these heterocycles. [9]

References

• 1 Kon Y. Usui Y. Sato K. Chem. Commun.  2007,  4399 
• 2 Carey FA. Organic Chemistry   McGraw-Hill; New York: . 
• 3 Moreau J. Duboc A. Hubert C. Hurvois J. Renaud J. Tetrahedron Lett.  2007,  48:  8647 
• 4 Hong B. Wu M. Tseng H. Liao J. Org. Lett.  2006,  8:  2217 
• 5 Kumar S. Malachowski WP. Hadaway JB. Londe JM. Carroll PJ. Jaller D. Metz R. Prendergast GC. Muller AJ. J. Med. Chem.  2008,  51:  1706 
• 6 Kim H. Dogutan DK. Ptaszek M. Lindsey JS. Tetrahedron  2007,  63:  37 
• 7 Clark AJ. Geden JV. Thom S. Wilson P. J. Org. Chem.  2007,  72:  5923 
• 8 Ko S. Lin C. Tu Z. Wang Y. Wang C. Yao C. Tetrahedron Lett.  2006,  47:  487 
• 9 Chauder BA. Lopes CC. Lopes RSC. da Silva AJM. Snieckus V. Synthesis  1998,  279