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Photochemical Ring Enlargement of Macrocyclic N ‐Phenyl Imides into Cyclophanes
Author(s) -
Heerklotz Jörg A.,
Fu Changchun,
Linden Anthony,
Hesse Manfred
Publication year - 2000
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/1522-2675(20000809)83:8<1809::aid-hlca1809>3.0.co;2-l
Subject(s) - chemistry , allylic rearrangement , ring (chemistry) , imide , yield (engineering) , irradiation , medicinal chemistry , quantum yield , fries rearrangement , stereochemistry , photochemistry , polymer chemistry , organic chemistry , catalysis , fluorescence , materials science , physics , quantum mechanics , nuclear physics , metallurgy
Allylic N ‐phenyl imides containing 12‐ and 14‐membered rings, such as compounds 3 and 12 , are easily synthesized by ring enlargement from cycloalkanones and phenyl isocyanates. Irradiation of 3 and 12 in EtOH and MeCN, with high‐ and low‐pressure Hg lamps, led, via the photo‐ Fries rearrangement, to the same primary products: the orthocyclophane 8 and the paracyclophane 9 from 3 ( Scheme 2 ), and the corresponding compounds 13 and 14 from 12 ( Scheme 3 ). Besides the primary photorearrangement products, secondary products, the aminocyclophanes 10 and 11 , or 15 and 16 , respectively, were also formed. The total yields of the four products were very high when the N ‐phenyl imides were irradiated in MeCN with a low‐pressure Hg lamp: 97 and 93%, respectively. If the para ‐position in 3 or 12 is blocked by a Me group, the para ‐photo‐ Fries rearrangement is prevented. In this case, only one primary photoproduct is formed: the corresponding orthocyclophane ( 17 or 23 , resp.). The most remarkable result was observed on irradiation of the 12‐membered N ‐(4‐tolyl) imide 5 in MeCN (low‐pressure lamp). It reacted nearly quantitatively to give only two products: 15‐methyl‐1‐aza[12]orthocyclophane‐2,12‐dione (=16‐methyl‐2‐azabicyclo[12.4.0]octadeca‐1(14),15,17‐triene‐3,13‐dione; 17 ) in 80% yield and 17‐amino‐14‐methyl[11]metacyclophane‐1,11‐dione (=17‐amino‐15‐methylbicyclo[11.3.1]heptadeca‐1(17),13,15‐triene‐2,12‐dione; 19 ) in 16% yield ( Scheme 5 ).