O-Bromobenzaldehydes

The Suzuki cross coupling product 151 obtained from 150 and o-bromobenzaldehyde on exposure to caesium fluoride furnished, via in situ capture of the resulting carbanion 152 by the proximate aldehyde group, the Peterson elimination product, the enamine 153 in 54% yield. 

The coupling of the arylboronic acid 1 with o-bromobenzaldehydes (2) leads directly to phenanthridines (3).3... 

Another system studied is the photostimulated reaction of o-bromobenzaldehyde or 2-bromoacetophenone (300) with SCH2C02Et as a nucleophile. The substitution product 301 in the basic condition forms the anion 302 which leads to benzothiophenes 303 (equation 184)288. The yields are only moderate due to the fragmentation of the radical-anion intermediate. 

This suggests that in the case that both intramolecular C- and 0-arylations are of geometrically equal possibility, the former preferentially takes place. The reaction of o-bromobenzaldehydes with dibenzylketones gives l,3-diaryl-2-naphthols that may be useful materials as bulky 0-ligands (Eq. 24) [62]. This cyclization involves palladium-catalyzed a-arylation and base-promoted dehy-drative condensation. Treatment of o-iodoanilines with ketones produces indole derivatives (Eq. 25) [63]. In this case, dehydrative condensation between the amino group and the carbonyl group occurs initially and the subsequent car-bopalladation (mechanism A) leads to the products. 

In contrast to the reaction in Eq. (73), treatment of o-bromobenzaldehydes as well as o-bromophenyl ketones with alkynes in the presence of ethanol gives cyclized products at the carbonyl carbon, i.e., indenols (Eq. 74) [147,148]. This reaction resembles that in Eq. (21). 

This strategy has been used to convert o-bromobenzaldehydes into phthalaldehydic acids (equation I).2... 

P-Lactams 28 were obtained from reaction of acylhydrazones with chloroacetyl chloride . A -Alkylation of acridine derivatives with 1,3-propane sultone gave 29. P-Phenethylamides gave 3,4-dihydroisoquinolines and N-sulfonyl gave isoquinolines 30. Nucleophilic substitution of 4-bromoisoquinoline gave the corresponding 4-substituted isoquinolines. o-Bromobenzaldehyde was reacted with allylamine and then homophthalic anhydride to afford 31. ... 

A general method for the synthesis of 5-deazaflavins involves the condensation of 6-substituted-aminouracils with o-halogeno-benzaldehydes in dimethylformamide for example,the reaction of (306) with o-bromobenzaldehyde gives (307) in 82% yield. 

On the other hand, Yamamoto and co-workers observed that the Pd-catalyzed reaction of o-bromobenzaldehyde (71) with 4-octyne in DMF using Pd(OAc)2 gave rise to the indenol 74 in 71 % yield. Also it was conhrmed that the indenol 74, once formed, was isomerized to the indanone 75 quantitatively in the presence of Pd(OAc)2 and AcOK [24]. Furthermore, reaction of o-bromoacetophenone (76) with 4-octyne afforded the substituted indenol 77 in 82% yield, which has no... 

Various cyclic compounds can be prepared by the reaction of ketones with bifunctional aryl halides. The jS-naphthol derivative 52 was obtained by a-arylation of dibenzyl ketone (14) with o-bromobenzaldehyde derivative 51, followed by aldol condensation [38], Also the indole derivative 54 was synthesized by the reaction of cyclohexanone with 2-iodoaniline (53). Formation of 54 may be explained by enamine formation at first, followed by intramolecular Mizoroki-Heck reaction, rather than via a-arylation [39],... 

Similar tandem cyclization reactions of o-bromobenzaldehydes have also been re-ported (Scheme 29). In these reactions, either Br or formyl group may react first. However, their mechanistic details are not very clear. 

Yet another type of cycUzation was observed for o-bromostilbenes, which actually competes with the second couphng step of o-dibromobenzene with styrene when only 1 equiv of styrene is used. o-Bromostilbene and substituted analogs, prepared from o-bromobenzaldehydes by Wittig-Homer-Emmons oleflnations, undergo efficient... 

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