Xyloccensins O and P, Unique 8,9,30-Phragmalin Ortho Esters from <i>Xylocarpus </i><i>g</i><i>ranatum</i>

Two unique 8,9,30-phragmalin ortho esters, xyloccensins O (<b>1</b>) and P (<b>2</b>), were isolated from the mangrove plant <i>Xylocarpus granatum</i>. They are a new type of ortho ester of phragmalin. The structures were determined by spectroscopic and single-crystal X-ray diffraction techniques. The biogenetic pathway to these new phragmalins was also proposed.