Indane-2-one

When indan-2-one (3) forms a Schiff s base with aniline and this is reduced with sodium borohydride, the aminoindane 4 is found. The acidic hydrogen is removed with sodium hydride and this is in turn... 

Most recently, Lappert and co-workers have found that the carbonylation of bis(i7-cyclopentadienyl)titanabenzocyclopentene resulted in the formation of Cp2Ti(CO)2 (1) and indan-2-one 47a). 

A one-step synthesis of isochromene itself has been reported from indene oxide (191) (66CC415). Irradiation of the epoxide in benzene affords two products, isochromene and indan-2-one, in similar quantities. It was proposed that initial fission of the carbon-carbon bond of the three-membered ring is followed by 1,4- or 1,2-hydrogen migration (Scheme 36). 

The Baeyer-Villiger oxidation of indan-2-one gives isochroman-3-one in good yield (49JCS1720). 

Catalysis of the enolization of indan-2-one (96 pKa = 12.2) by a-, j8-, y-, and modified cyclodextrins (of similar pKa) indicate that the latter act as general bases.139 There is also an inclusion component to the catalysis saturation kinetics consistent with 1 1 binding are observed for enolate formation. 

Tee s group has reported on the catalysis of enolization of indan-2-one (200) by a-CD, [1-CD, y-CD, hydroxyethyl-jS-CD, and hydroxypropy I -/i-C D, all of which accelerate the reaction by up to 22-fold, but dimethyl-jS-CD slows it by about half.170 These workers have also looked at the effect of alcohols on the basic cleavage of m-nitrophenyl hexanoate by /1-CD.171 Finally, they have been examining the reaction of a-amino acid anions with p-nitrophenyl acetate and hexanoate in the presence of [1-CD.172... 

Whereas a triplet 1,4-biradical has been assigned as the most probable intermediate at that time, later work on intramolecular trapping reaction favored the assumption of radical ion pairs [46]. Efficient lactonization reaction to form 51 during irradiation of pent-4-enoic acid 50 and 48 accounts for an olefin radical cation which undergoes electrophilic addition towards the carboxyl group. Another type of rearrangement has been detected in the photoreaction of tetramethylallene and 48 [47]. 5-Hydroxy-indan-2-ones 52 are formed in high yields probably via instable spiro-oxetanes 49b as intermediates. 

The anionic form usually obtained in using enamines as synthesis reagents is usually the allyl form. Thus, Blomquist and Moriconi46" showed that, by reacting a solution of the pyrrolidine enamine of indan-2-one in tetrahydrofuran with w-butyl lithium in -hexane at —65 °C (equation 22), the proton removal is complete in about 10 min. 

Isochromane-3-oae. lsochromane-3-one (2) can be prepared in 68 % yield (pure) by Baeyer-Villigcr oxidation of indane-2-one (1) with 90% hydrogen peroxide, sulfuric... 

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