Dihydroisocoumarins. I. Synthesis of 3,4-Dihydro-7,8-dimethoxyisocoumarin

Abstract

VOL. 26through an 18-in. packed column gave unchanged tetramathylcyclobutanedione and 263 g. (61%) of 2,2,4,4tetrametnyl-3-phenyliminocyclobutanone (X), b.p. 124-125' (7 mm.), nF 1.5165.Anal. Calcd. for G4H"NO: C, 78.1; H, 8.0; N, 6.5.Found: C, 77.8; H, 7.9; N, 6.4.The infrared spectrum had bands a t 5.55 p (cyclobutanone) and 5.9 p (C==N, where carbon ia part of strained ring).The distillation reaidue (98 g.) crystallized on cooling. After recrystalhation from ethyl alcohol, 81 g. (28%) of 2,2,4,4-tet"thyl-N,N'4iphenyl-1 ,3-cyclobutanediimineJ m.p. 140-142', was recovered. a#,.# ,4-T&wwihyLNJN'-diphyLl ,scydobuhnedimine (XI). A solution of 140 g. of tetramethyl-1,3-cyclobutanedione, 232.5 g. of &e, and 5 g. of p-toluenesulfonic acid in 700 ml. of toluene was refluxed through a 10-in. packed column equipped with a Dean4tark trap. The theoretical amount of water (36 ml.) was collected in 8 hr. The reaction solution was washed with sodium bicarbonate solution and with water, dried over magndum d a t e , filtered, and evaporated on the steam bath. The reaidual slurry of cryatale was filtered and the crystals were washed with cold hexane.

Cyclopiamines A and B, novel oxindole metabolites of Penicillium cyclopium westling

“…The structure and relative stereochemistry of cyclopiamine A (1) were deduced from a correlation of its physico-chemical properties with those of cyclopiamine B (2a). This paper relates the data from the chemical and physicochemical investigations of cyclopiamines A and B, the synthesis of a model compound (8), and the X-ray analysis of cyclopiamine 33. Cyclopiamine B (2a) had U.V.…”

Isocoumarins. Developments Since 1950

“…The alcohol can be cyclized by heat to 3,4-dihydroisocoumarin. This procedure has been used to prepare several methoxy-3,4-dihydroisocoumarins, among them 5,8-, 6,7-, and 7,8-dimethoxy-3,4-dihydroisocoumarin (18,19,177). As discussed in section IIB, the N-bromosuccinimide procedure can be used to make isocoumarins from the corresponding 3,4-dihydroisocoumarins.…”