The m-xylylene moiety was employed as rigid spacer in intramolecular glycoside bond formation.
Fifteen-membered macrocycle formation starting from 6-O-linked donor and 6- and 4-O-linked
acceptor (5a,b, 6b) led exclusively to β(1-4)- and β(1-6)-linked compounds 7β and 8β, respectively,
which gave cellobioside and gentiobioside derivatives. The glycosylation yields could be improved
by 14-membered macrocycle formation. In the four cases studied, the donor was 6-O-linked to the
spacer. For the acceptor linkage to the spacer and the accepting hydroxy group, relative d-/l-threo-
and d-/l-erythro-arrangements were chosen. Standard glycosylation conditions led in three cases
(13, 14, 23) only to β-linkage in high yield (16β, 17β, 25β). For the transformation of 24, having a
d-erythro-arrangement in the acceptor moiety, the α-anomer 26α was preferentially obtained.
Limitation of the conformational space of the donor and the acceptor as in 31, which is
stereochemically identical with 24, led to the corresponding α-glycoside 32α in 87% yield. Synthesis
of a pseudo mirror image of 23 [having 6-(d)/3-(d-threo)-arrangement], namely 35, having 3(l)/6-(l-threo)-arrangement of the donor and acceptor moieties, expectedly gave only α-glycoside 36α in
very high yield. Thus, the efficiency and versatility of this conceptual approach to intramolecular
glycoside bond formation is exhibited.
Aromatic aldols and 1,5-diketones with abstractable γ-hydrogen atoms are highly photoactive cage molecules for the release of fragrance carbonyl compounds (aldehydes and Michael ketones, respectively). Aldols 3a-d are easily accessible by Mukaiyama addition and are cleaved to form the substrates with high quantum yields under solar radiation. By tuning the properties of the chromophores, a series of δ-damascone cages 5 were developed that can be used for selective and fast (5a,e) or slow (5b,d) release of fragrances under air and solar irradiation. The intermediates of the Norrish II process were observed by laser transient absorption spectroscopy.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.