I'm very late to this, but one of the significant figures in the synthesis, Verne Grant, died in May. Grant's book The Origin of Adaptations (1963) was one that influenced a lot of theorising about evolution. His essay on species concepts in 1957 pointed out that botanical notions of species had to be very different to the reigning Mayrian biospecies concept.
Grant, Verne. 1957. The Plant Species in Theory and Practice. In The Species Problem, edited by E. Mayr. Washington DC: American Association for the Advancement of Science.
———. 1963. The origin of adaptations. New York: Columbia University Press.
I haven't read the Origins of Adaptations for years, but Grant's point about the difference between the way plants and animals evolve has shaped my thinking about evolution and, more generally, about science ever since I first encountered his book.