Yu, Shuling et al. published their research in Organic Letters in 2021 | CAS: 1190-39-2

malonic acid dibutyl ester (cas: 1190-39-2) belongs to esters. Esters typically have a pleasant smell; those of low molecular weight are commonly used as fragrances and are found in essential oils and pheromones. Esters contain a carbonyl center, which gives rise to 120° C–C–O and O–C–O angles. Unlike amides, esters are structurally flexible functional groups because rotation about the C–O–C bonds has a low barrier. Their flexibility and low polarity is manifested in their physical properties; they tend to be less rigid (lower melting point) and more volatile (lower boiling point) than the corresponding amides. Synthetic Route of C11H20O4

Synthesis of Cyclopentenones through Rhodium-Catalyzed C-H Annulation of Acrylic Acids with Formaldehyde and Malonates was written by Yu, Shuling;Hong, Chao;Liu, Zhanxiang;Zhang, Yuhong. And the article was included in Organic Letters in 2021.Synthetic Route of C11H20O4 This article mentions the following:

An efficient rhodium-catalyzed protocol for the synthesis of cyclopentenones I (R1 = Et, Bn, c-hexyl, etc.; R2 = H, Me, Et, Ph; -R1R2– = -(CH2)3-, -(CH2)4-; R3 = Me, Et, n-Pr, i-Pr, n-Bu) based on a three-component reaction of acrylic acids, formaldehyde, and malonates via vinylic C-H activation is reported. Exploratory studies showed that 5-alkylation of as-prepared cyclopentenones could be realized smoothly by the treatment of a variety of alkyl halides with a Na2CO3/MeOH solution Excess formaldehyde and malonate led to a multicomponent reaction that afforded the multisubstituted cyclopentenones II (R1 = n-Bu, 3-FC6H4, Ph(CH2)2, etc.; R2 = H, Me, Et, etc.; R3 = Me, Et, n-Pr, i-Pr; -R1R2– = -(CH2)4-) through a Michael addition In the experiment, the researchers used many compounds, for example, malonic acid dibutyl ester (cas: 1190-39-2Synthetic Route of C11H20O4).

malonic acid dibutyl ester (cas: 1190-39-2) belongs to esters. Esters typically have a pleasant smell; those of low molecular weight are commonly used as fragrances and are found in essential oils and pheromones. Esters contain a carbonyl center, which gives rise to 120° C–C–O and O–C–O angles. Unlike amides, esters are structurally flexible functional groups because rotation about the C–O–C bonds has a low barrier. Their flexibility and low polarity is manifested in their physical properties; they tend to be less rigid (lower melting point) and more volatile (lower boiling point) than the corresponding amides. Synthetic Route of C11H20O4

Referemce:
Ester – Wikipedia,
Ester – an overview | ScienceDirect Topics