Homophthalic Anhydride Research Articles

Enantioselective Synthesis of α-Aryl-β-amino Acids from N-Boc Imines and Homophthalic Anhydrides

Enantioselective Synthesis of α-Aryl-β-amino Acids from N-Boc Imines and Homophthalic Anhydrides

Front Cover Picture: Enantioselective Synthesis of Oxindole‐Derived α‐Aryl‐β‐Amino Acid Derivatives and δ‐Lactams with Homophthalic Anhydrides (Adv. Synth. Catal. 24/2019)

Front Cover Picture: Enantioselective Synthesis of Oxindole‐Derived α‐Aryl‐β‐Amino Acid Derivatives and δ‐Lactams with Homophthalic Anhydrides (Adv. Synth. Catal. 24/2019)

Enantioselective Synthesis of Oxindole‐Derived α‐Aryl‐β‐Amino Acid Derivatives and δ‐Lactams with Homophthalic Anhydrides

AbstractA highly diastereo‐ and enantioselective Mannich reaction of isatin‐derived N‐Boc imines with homophthalic anhydrides is disclosed for the first time, which allows the direct synthesis of a wide range of oxindole‐derived α‐aryl‐β‐amino acids with two adjacent carbon stereogenic centers in a highly stereoselective fashion (up to >95:5 dr & >99% ee). The resulted Mannich adducts can be easily converted to chiral spirocyclic δ‐lactams with retention of the stereoslectivities.magnified image

Highly Enantioselective Catalytic Kinetic Resolution of α-Branched Aldehydes through Formal Cycloaddition with Homophthalic Anhydrides.

A new catalytic methodology was developed to promote an efficient one-pot kinetic resolution of racemic aldehydes with selectivity (s*) of up to 91 (99:1 d.r., >99 % ee) in a cycloaddition reaction with enolizable anhydrides to afford dihydroisocoumarin products (a core prevalent in natural products and molecules of medicinal interest) containing three contiguous stereocentres.

Hydroxylamine as an ammonia equivalent: access to NH-tetrahydroisoquinolonic derivatives from aldoximes by the Castagnoli–Cushman reaction followed by reduction

A novel synthetic protocol towards trans-NH-tetrahydroisoquinolonic acid esters is based on the Castagnoli–Cushman reaction between aromatic aldehyde oximes and homophthalic anhydride, followed by esterification and TiCl3-promoted reduction. The scope of the method with respect to the aromatic portion (both electron-rich and electron-deficient) is broader compared to the earlier described approaches, which makes it a suitable synthetic strategy for the structure–activity exploration.

Synthesis of novel trans-4-(phthalimidomethyl)- and 4-(imidazol-1-ylmethyl)-3-indolyl-tetrahydroisoquinolinones as possible aromatase inhibitors

The reaction of homophthalic anhydride with 1H-indol-3-carbaldimines was used for the preparation of trans- and cis-2-alkyl-3-indolyl-1-oxotetrahydroisoquinolin-4-carboxylic acids 3a–d. The stereochemistry of the reaction was investigated by means of 1H NMR spectroscopy. The carboxylic group of trans-3a–d was transformed stereoselectively via 4-hydroxymethyltetrahydroisoquinolin-1-ones into 4-(phthalimidomethyl)-derivatives trans-6a,b and 4-(imidazolylmethyl)-derivatives trans-8b–d. Compounds trans-6a,b and 8b–d were tested for antiaromatase activity, and the preliminary results showed that the phthalimidomethylisoquinolinone trans-6b at 50 μM concentration decreased the aromatase enzyme activity with 40%.

An efficient solvent-free synthesis of 2-(alkylamino)-2-oxo-1-arylethyl-6,12-dioxo-6,12-dihydroindolo[1,2-b]isoquinoline-11-carboxylate derivatives via four-component reaction.

A one-pot approach for the synthesis of a new series of 2-(alkylamino)-2-oxo-1-arylethyl-6,12-dioxo-6,12-dihydroindolo[1,2-b]isoquinoline-11-carboxylate derivatives via a four-component reaction using isatin, homophthalic anhydride, cyclohexyl isocyanide and an aldehyde is described. This method has several advantages such as being catalyst- and solvent-free reaction and a high-efficiency process with high to excellent yields.

Catalytic Asymmetric Cycloadditions between Aldehydes and Enolizable Anhydrides: cis-Selective Dihydroisocoumarin Formation.

In the presence of a trityl-substituted cinchona alkaloid-based catalyst, homophthalic, aryl succinic, and glutaconic anhydride derivatives reacted with aromatic and aliphatic aldehydes to produce cis-lactones in up to 90:10 dr and 99% ee. A DFT study has shown how the catalyst is uniquely able to bring about the opposite sense of diastereocontrol to that usually observed.

The Castagnoli-Cushman reaction in a three-component format

The first example of the Castagnoli-Cushman reaction of homophthalic acid with an amine and an aldehyde conducted in a three-component format is reported. This new protocol employs no dehydrating agents and, unlike the traditional Castagnoli-Cushman reaction of homophthalic anhydride, allows simultaneous mixing of all three reagents and provides good to excellent yields of trans-configured tetrahydroisoquinolonic acids.

Aldazines in the Castagnoli–Cushman Reaction

Aldazines were employed in the Castagnoli–Cushman reaction of homophthalic anhydride for the first time. The reaction proved to be distinctly diastereoselective when conducted at room temperature in acetonitrile, yielding predominantly the kinetic cis-configured adduct as a racemate. Thermodynamically more stable trans-configuration could be attained either via heating the cis-configured product in DMSO or via the action of a base (imidazole) in the course of CDI-promoted esterification or amidation of the carboxylic acid function in the initial adducts. Further manipulation of the remaining N-acylhydrazone moiety in the latter led to N-alkyl- or fully unprotected N-aminolactams.

Facile Access to 3-Unsubstituted Tetrahydroisoquinolonic Acids via the Castagnoli–Cushman Reaction

Hitherto undescribed 3-unsubstituted tetrahydroisoquinolonic acids (isolated as their respective methyl esters) were accessed for the first time by the uncatalyzed, thermally promoted Castagnoli–Cushman reaction (CCR) of homophthalic anhydride (HPA) and a series of 1,3,5-triazinanes. The moderate yields observed in some cases are most likely associated with a persistent impurity also formed in these reactions. The new scaffold is expected to find novel medicinal utility (compared to the traditional CCR adducts) because it lacks a substituent at the 3-position.

Synthesis and antitumor evaluation of novel tetrahydrobenzo[4′,5′]thieno[3′,2′:5,6]pyrimido[1,2-b]isoquinoline derivatives

ABSTRACTIn the present study, a novel 8,9,10,11-tetrahydro-7H,14H-benzo[4′,5′] thieno[2′,3′:4,5]-1,3-oxazino[3,2-b]isoquinoline-7,14-dione 5 was prepared by condensation of 2-amino-3-carbethoxy-4,5,6,7-tetrahydrobenzothiophene with homophthalic anhydride under microwave irradiation, followed by alkaline hydrolysis and cyclization using acetyl chloride. Compound 5 was further allowed to react with different nitrogen nucleophiles to get new tetrahydrobenzothienopyrimido isoquinolinone derivatives. The structures of the prepared compounds were elucidated by IR, 1H-NMR, 13C-NMR, and mass spectroscopy. The newly prepared compounds were tested in vitro against a panel of two human tumor cell lines, namely, hepatocellular carcinoma (liver) HepG2, and mammary gland breast MCF-7. Almost all the tested compounds showed satisfactory activity.

Catalyst-free [4 + 2] cyclization of para-quinone methide derivatives with homophthalic anhydrides.

The title reaction has been established, which offers a useful method for the construction of dihydrocoumarin frameworks in generally good chemical yields (up to 99%) and high diastereoselectivities (up to >95 : 5 dr). This reaction represents a good example of [4 + 2] cyclizations of para-quinone methide derivatives with electron-rich reaction partners under catalyst-free conditions.

Mixed carboxylic-sulfonic anhydride in reaction with imines: a straightforward route to water-soluble β-lactams via a Staudinger-type reaction.

The first example of employing a mixed carboxylic-sulfonic anhydride in reaction with imines is reported. Unlike its well-studied isostere homophthalic anhydride, benzo[c][1,2]oxathiin-3(4H)-one 1,1-dioxide gave no product of a formal [4 + 2] cycloaddition and only followed an alternative reaction pathway toward β-lactams, presumably, via a formal [2 + 2] cycloaddition (a Staudinger-type reaction). Optimized reaction conditions involve the use of triethylamine as a base promoter, which also allows isolating the product β-lactam benzene sulfonic acids as respective triethylammonium salts by conventional column chromatography. The reaction shows some preference to trans-isomer formation; pure diastereomers can be isolated in some cases.

Application of Homophthalic Anhydrides as 2C Building Blocks in Catalytic Asymmetric Cyclizations of ortho‐Quinone Methides: Diastereo‐ and Enantioselective Construction of Dihydrocoumarin Frameworks

AbstractA catalytic asymmetric [4+2] cyclization of ortho‐quinone methides with homophthalic anhydrides in the presence of chiral squaramide‐tertiary amine has been established. This method provides dihydrocoumarin frameworks in excellent diastereoselectivities (all >95:5 dr) and high enantioselectivities (81%–98% ee). This reaction represents the first application of homophthalic anhydrides as 2C building blocks in catalytic asymmetric cyclizations. In addition, this approach not only provides a useful method for constructing enantioenriched dihydrocoumarin frameworks but also advances the chemistry of catalytic asymmetric cyclizations of ortho‐quinone methides.magnified image

Stereochemistry and reactivity of the HPA-imine Mannich intermediate

Homophthalic anhydride (HPA) typically reacts rapidly with benzalimines to afford the formal [4+2] adduct, a 1,2,3,4-tetrahydroisoquinolin-1-one-4-carboxylic acid. The stereochemical outcome of this reaction is consistent with an open transition state comprising an iminium species and enolized HPA, leading to a short-lived amino-anhydride intermediate. In the case of N-tert-butylbenzalimine, this Mannich-type intermediate, which would normally cyclize at low temperature to a single isomer of the delta-lactam, is intercepted by base treatment to afford beta-lactam products. A pathway featuring ketene formation followed by ring closure is implicated.

Complications in the Castagnoli-Cushman reaction: An unusual course of reaction between cyclic anhydrides and sterically hindered indolenines

Attempted reaction of indolenines (which represent rather sterically hindered cyclic imines) with a series of dicarboxylic acid anhydrides yielded no expected product, the Castagnoli-Cushman lactam. Instead, products presumably formed via N-acyliminium species trapping by a carboxylate anion. Among them, hydrolytically labile 2:2 adducts of an indolenine and a cyclic anhydride, containing a 16-membered cyclic core, are particularly intriguing. This result contradicts the recently reported successful Castagnoli-Cushman reaction of indolenines with homophthalic anhydride suggesting a mechanistic switch in the course of the reaction.

A speedy route to sterically encumbered, benzene-fused derivatives of privileged, naturally occurring hexahydropyrrolo[1,2-b]isoquinoline

A series of 15 benzene-fused hexahydropyrrolo[1,2-b]isoquinolonic acids with substantial degree of steric encumbrance has been prepared via a novel variant of the Castagnoli–Cushman reaction of homophthalic anhydride (HPA) and various indolenines. The employment of a special kind of a cyclic imine component reaction allowed, for the first time, isolating a Mannich-type adduct between HPA and an imine component which has been postulated but never obtained in similar reactions.

Efficient MW‐Assisted Synthesis of Some New Isoquinolinone Derivatives With In Vitro Antitumor Activity

An efficient and convenient synthesis of novel [1,3]oxazino[3,2‐b]isoquinoline‐5,12‐dione derivative 4 was achieved by the reaction of anthranilic acid with homophthalic anhydride under microwave irradiation, followed by cyclization with acetic anhydride. Some new isoquinolinone and fused isoquinolinone derivatives were prepared via reaction of compound 4 with different nitrogen nucleophiles by using reflux and a focused microwave reactor. Microwave irradiation favored the formation of the desired products with improved yields and shortened reaction times. This is a simple and green method for the synthesis of isoquinolinone derivatives. The structures of the prepared compounds were elucidated by IR, 1H‐NMR, and mass spectroscopy. Some of the newly prepared compounds were tested in vitro against a panel of three human tumor cell lines, namely, hepatocellular carcinoma (liver) HepG2, colon cancer HCT‐116, and mammary gland breast MCF‐7. Almost all of the tested compounds showed satisfactory activity.

Synthesis of Lactams from Imines and Homophthalic Anhydride

Key words isoquinolinones - asymmetric catalysis - hydrogen bonding - cycloaddition - imines - organocatalysis