With copious quantities of key precursor 38 in hand, divergent access to a variety of naturally occurring STX analogs was exemplified as outlined in Scheme 2A. By enlisting the extensive precedent of related intermediates towards this end, a modification of Nagasawa and Du Bois' protocol could be used to access M2 (11) cyclization with the tert-butylimino-tri(pyrrolidino)phosphorane (BTPP) to macrocycle 44 , and finally (4) ring opening/carbamate installation using chlorosulfonyl isocyanate (CSI) and formic acid (47% yield over 2 steps). It is worthwhile to note that (+)-dcSTX ( ) is a known precursor to natural products 7 (b-dcSTXol) 46 and 8 (B1) 47 thus constituting formal syntheses of those as well.