Three methods for producing anhydrides of arylfuran and arylpyran pseudoacids were explored. These included thermal dehydration, phosgene or thionly chloride activation and decomposition, and dicyclohexylcarbodiimide activation and coupling. Derivatives of the cyclic forms of o-formylbenzoic acid, o-acetylbenzoic acid, 2-carboxyphenylacetaldehyde and of 4,4-dimethyl-3,4-dihydro-3-hydroxy-[1H]-isobenzopyran-1-one were formed including dipseudoanhydides and normal-pseudo anhydrides. Crystal and molecular structures for meso and (R,R/S,S)-bis(1[3H]-isobenzofuranone-3-yl)ether, (R,R/S,S)-bis(3-methyl-1[3H]-isobenzofuranone-3yl)ether, meso (3,4-dihydro-[1H]-isobenzopyran-1-one-3-yl)ether, 3-benzoyloxy-1[3H]-isobenzofuranone, 3-benzoyloxy-3-methyl-1[3H]isobenzofuranone, 3-(4′-nitrobenzoyloxy)-4,4-dimethyl-3,4-dihydro-[1H]-isobenzopyran-1-one, and (1[3H]-isobenzofuranone-3-yl)(4,4,dimethyl-3,4-dihydro-[1H]-isobenzopyran-1-one-3-yl)ether are reported. Endocyclic pseudoacyl C–O bonds are always longer than the exocyclic pseudoacyl C–O bonds. It is possible to refine the previously established C–O bond length dependencies on the pKa (of the conjugate acids) of the leaving groups for 3-substituted 1-[3H]-isobenzofuranones. Of six dipseudoanhydrides studied, conformations are found with exocyclic C–O(ether) linkages synclinal to the endocyclic C–O and away from the ring (exo conformation) in two meso structures, two of three RR/SS forms and in a chiral unsymmetrical form. An endo conformation is observed in one of the RR/SS forms. In three normal-pseudo anhydrides, both endo and exo conformations are observed.Graphic AbstractSynthetic methods for formation of anhydrides of several arylfuran and arylpyran pseudoacids are described, and the pseudoacyl C–O bond length trends are determined for leaving groups spanning over 30 pKa units.

中文翻译：

---

芳基呋喃和芳基吡喃伪酸的酸酐：形成和结构；伪邻甲酰基苯甲酸衍生物的 C-O 键长趋势

探索了三种生产芳基呋喃和芳基吡喃假酸酐的方法。这些包括热脱水、光气或氯化亚砜活化和分解，以及二环己基碳二亚胺活化和偶联。形成了环状形式的邻甲酰基苯甲酸、邻乙酰苯甲酸、2-羧基苯乙醛和 4,4-二甲基-3,4-二氢-3-羟基-[1H]-异苯并吡喃-1-one 的衍生物，包括二假酸酐和正常的假酸酐。内消旋和 (R,R/S,S)-双(1[3H]-异苯并呋喃酮-3-基)醚的晶体和分子结构，(R,R/S,S)-双(3-甲基-1[ 3H]-isobenzofuranone-3yl)ether, meso (3,4-dihydro-[1H]-isobenzopyran-1-one-3-yl)ether, 3-benzoyloxy-1[3H]-isobenzofuranone, 3-benzoyloxy-3-甲基-1[3H]isobenzofuranone, 3-(4'-nitrobenzoyloxy)-4,4-dimethyl-3,4-dihydro-[1H]-isobenzopyran-1-one, 和 (1[3H]-isobenzofuranone-3-yl)(4,4,dimethyl-3,4-dihydro-[1H]-isobenzopyran-1-one-3-yl)ether 报道。环内假酰基 C-O 键总是比环外假酰基 C-O 键长。对于 3-取代的 1-[3H]-异苯并呋喃酮，可以改进先前建立的 C-O 键长度对离去基团 pKa（共轭酸）的依赖性。在研究的六种双假酸酐中，发现了具有向内环 C-O 向斜且远离环（外构象）的环外 C-O（醚）键的构象，包括两种内消旋结构、三种 RR/SS 形式中的两种和手性不对称形式。在 RR/SS 形式之一中观察到内构象。在三种正常的假酸酐中，观察到内型和外型两种构象。