
TY  - JOUR
A1  - Brimble, Margaret A. 
A1  - Chan, Seng H. 
T1  - Synthesis of 7-Methoxy-3&#8242;,4&#8242;,5&#8242;,6&#8242;-tetrahydrospiro-[isobenzofuran-1(<emph type="2">3H</emph>),2&#8242;-pyran]-3-one and 5,7-Dimethoxy-3&#8242;,4&#8242;,5&#8242;,6&#8242;-tetrahydrospiro[isobenzofuran-1(<emph type="2">3H</emph>),2&#8242;-pyran]-3-one
JF  - Australian Journal of Chemistry
JO  - Aust. J. Chem.
Y1  - 1998
VL  - 51
IS  - 3
SP  - 235
EP  - 242
KW  - 
UR  - https://doi.org/10.1071/C97193 
N2  - The synthesis of novel aryl spiroketals, which contain a similar substitution pattern to that present in the antifungal agents the papulacandins, is described. Thus, spiroketal (7) was obtained from acid-catalysed cyclization of the keto alcohol (13), and spiroketal (8) was obtained from acid-catalysed cyclization of keto alcohols (12) and (19). Keto alcohols (12), (13) and (19) in turn were prepared by ortho-directed lithiation of amides (10), (11) and oxazoline (17) respectively, followed by reaction with &#948;-valerolactone. Substitution of the aromatic ring occurred at the sterically hindered position ortho to both the methoxy and ortho-directing metalation group. In an alternative approach to the synthesis of the desired spiroketals, two palladium(0)-catalysed coupling strategies were examined. The Stille coupling between the aryl stannane (24) and iodoglucal (25) resulted in a low yield of the aryl C-glycoside (21). Likewise, a low yield for the same coupled product (21) was achieved by a Suzuki coupling between the arylboronic acid (26) and iodoglucal (25). 
ER  -

