Tetrahydrocannabiphorol

Tetrahydrocannabiphorol is a potent phytocannabinoid, a CB₁ and CB₂ receptor agonist which was known as a synthetic homologue of tetrahydrocannabinol, but for the first time in 2019 was isolated as a natural product in trace amounts from Cannabis sativa.
THCP is structurally similar to Δ⁹-THC, the main active component of cannabis, but with the pentyl side chain extended to heptyl. Since it has a longer side chain, its cannabinoid effects are "far higher than Δ⁹-THC itself." Tetrahydrocannabiphorol has a reported binding affinity of 1.2 nM at CB₁, approximately 33 times that of Δ⁹-THC, however this does not mean it's 33x stronger per milligram.
THCP was studied by Roger Adams as early as 1942.

Isomers

Delta-3-THCP

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The Δ³/Δ^6a isomer Δ³-THCP was synthesised in 1941, and was found to have around the same potency as Δ³-THC, unlike the hexyl homologue parahexyl which was significantly stronger.

Delta-8-THCP

The Δ⁸ isomer is also known as a synthetic cannabinoid under the code name JWH-091. It's unconfirmed whether or not JWH-091 is found naturally in cannabis plants. JWH-091 has approximately double the binding affinity at the CB₁ receptor in comparison to Δ⁹-THC or Δ⁸-THC, but appears significantly lower in vitro than the binding activity of Δ⁹-THCP

Natural cannabis occurrence

The Δ⁹ isomer of THCP occurs naturally in cannabis plants, but in very small amounts. A 2021 study reported the content of Δ⁹-THCP ranging from 0.0023% to 0.0136% without correlation to THC percentage in Δ⁹-THC-dominant strains of cannabis; that study failed to detect THCP in CBD-dominant strains.