Isochroman-3-one synthesis

Acetanilides, benzoyl-colour couplers in colour photography, 1, 372 Acetanilides, pivaloyl-colour couplers in colour photography, 1, 372 Acetazolamide — see l,3,4-Thiadiazole-2-sulfonamide, 5-acetamido-Acetic acid, acetamidocyano-ethyl ester, 1, 307 Acetic acid, 2-acylphenyl-isochroman-3-one synthesis from, 3, 858 Acetic acid, 3-benzo[6]thiophenyl-biological activity, 4, 912 Acetic acid, l,2-benzoxazol-3-yl-electrophilic substitution, 6, 48... 

Dicoumarol — see Coumarin, 3,3 -methylenebis(4-hydroxy-Dictamnine biosynthesis, 4, 992 occurrence, 4, 989 pharmacology, 4, 992 synthesis, 4, 990 Dicyanocobyrinic acid heptamethyl ester, 4, 422 Dicycloalkaselenophenes synthesis, 4, 968 Dicyclohexa-1,4-diselenins thermolysis, 4, 968 Dieckmann condensation chroman-3-one synthesis by, 3, 854 isochroman-4-one synthesis by, 3, 859 oxoindolizidine synthesis by, 4, 471... 

Homofolic acid, 5,11-methenyl-tetrahydro-biological activity, 3, 327 Homofolic acid, tetrahydro-biological activity, 3, 327 Homoisoflavanones occurrence, 3, 722 thermoisomerization, 3, 722 thermolysis, 3, 728 Homolytic reactions heterocyclic compounds reviews, 1, 74 Homophthalic acid isocoumarins synthesis from, 3, 830 synthesis, 3, 830 Homophthalic anhydride isochroman-l-one synthesis from, 3, 860 20a-Homoporphyrin nomenclature, 1, 30 Homopterocarpin isolation, 4, 998 ( )- D- Homotestosterone synthesis, 1, 453 Homer-Emmons reaction chromene synthesis by, 3, 749 Hortiacine isolation, 3, 149 Hortiamine isolation, 3, 149... 

A -0-2-Isocephem-4-carboxylic acid, 1-P-phenoxyacetamido-3-methyl-1 -oxo-synthesis, 1, 430 Isochroman, 1,3-diphenyl-synthesis, 3, 787, 788 Isochroman, 3,4-diphenyI-conformation, 3, 631 Isochroman, 2-methyl-synthesis, 3, 788 Isochroman, 3-phenyl-synthesis, 3, 788 Isochroman, (-)-)-(i )-3-phenyI-stereoselective synthesis, 3, 789 Isochroman-4-carboxylic acid, l-oxo-3-phenyl-synthesis, 3, 860 Isochroman-I,3-diones, 4-acyI-synthesis, 3, 831 Isochromanols dehydration, 3, 767 isochroman synthesis from, 3, 789 Isochroman-1-one, 3-aryl-synthesis, 3, 858, 860... 

A convenient synthesis of isochroman-3-one is based on the reaction of phenylacetic acids with formalin and concentrated hydrochloric acid (760S(55)45>. An indication of the value of the isochromanone as a synthetic intermediate is given in this procedure. 

Synthesis of the isochroman-3-one 1167 can be achieved by a nickel-catalyzed intermolecular cyclization of the ortho-haloester 1166 and benzaldehyde, with the ( )-isomer predominating in the product (Equation 454) <2004CEJ2991>. 

The carbonylation of (2-ethynylphenyl)methanol is catalyzed by Pd(OAc)2 in the presence of 2-(diphenylphos-phino)pyridine (2-PyPPh2) to provide 4-methyleneisochroman-3-one, isolated in poor yield due to its instability (Equation 456) <2002TL753>. The synthesis of isochroman-3-one can be achieved by a palladium and Hi-mediated carbonylation of l,2-bis(hydroxymethyl)benzene <1998BCJ723>. 

Treatment of pentasubstituted benzene 1169 with an excess of paraformaldehyde in the presence of ZnCl2 under acidic conditions successfully installs a chloromethyl group ortho- to the acetic acid substituent, furnishing a mixture of 1170 and the cyclized isochroman-3-one 1171. As these acidic conditions are not themselves enough to totally finish the cyclization, basic hydrolysis is conducted to complete the cyclization to the isochroman-3-one 1171, a key intermediate during a synthesis of mimosamycin (Scheme 288) <2000JOC635>. 

Fukumoto et al have taken advantage of the propensity for inward rotation of an acyl group to prepare the isochroman-3-one (36), an intermediate in their synthesis of geneserine, a constituent of the calabar bean. The conversion of the benzocyclobutene (37) to (36) proceeds via ring opening to the o-quinodimethane (38) followed by cyclization and a 3,3-sigmatropic rearrangement. 

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