Modular syntheses of naturally occurring lamellarin ε (5) and the synthetic analogue dehydrolamellarin J (6), both of them promising lead candidates for anticancer activity, were accomplished in high overall yields. Key steps in these routes are a late‐stage installation of the central pyrrole core by [4 + 1] cyclocondensation between ethyl bromoacetate and an enaminone possessing the remaining components of the lamellarin skeleton; and our recently revealed demethylative lactonization for building the chromenone components. Additionally, a mild and nearly quantitative new method for cleaving isopropyl‐protected phenols at room temperature with the comparatively green reagent methanesulfonic acid has been developed. The feasibility of exploiting the simplicity and efficiency of the new reactions on a multi‐gram scale was demonstrated by preparing over 25 g of dehydrolamellarin J, one of the most cytotoxic anticancer agents in the lamellarin family, without the need for chromatographic purification of intermediates.