Based on PM Naftali Bennett's interview, he was dispatched to Moscow at Z's behest knowing he was able to secure a relationship with Putin. Israel at the time was in a tough position not to take sides in this war, so Bennett thought and agreed as a mediator, Israel will be spared having to take sides and remain neutral. So PM Naftali visited Moscow and met with Putin to try and strike a ceasefire.
There were 2 very important information Zelensky gave to Bennett.
1. Find out if Putin is really going to have him assassinated.
2. If Moscow open for diplomacy and a ceasefire treaty.
When PM B arrived and spoke with Putin, he asked him squarely if Putin can promise not to have Z assassinated, to which Putin told PM B that he's giving his word he will not attempt to get him assassinated.
When that meeting concluded before he even reached the airport, PM B phoned Z about Putin's promise.
(pp)
Z: "Are you sure his promised he will not do this?"
B: "He promised!"
Now if all of you recall, at the onset of this SMO, Z cowered deep in a bunker and every video he released were done on green screens with Kiev as a background.
So shortly after that phonecall with B, he released a non-green screened video declaring he is not afraid of Putin.
Anyway, Turkey had been fairly neutral in this war thus far and it really didnt want to tarnished its relationship with Moscow despite it being a NATO member. It was decided Istanbul will be site for these talks. B kept the US/UK/Germany/FRance in the loop the entire time. So when he left Moscow, he went to Germany as his first stop to present Moscow's willingness for a ceasefire, talks and negotiation.
Z had given B a summary list of what he can offer for the ceasefire. Foremost that Russia immediately scale back its military operation at the onset of the meeting, that Ukraine will not host any non-state military base within its borders, not sign up for NATO membership but should be open for EU membership. The subject of Donest/Crimea to be open for discussion and be repatriated back to Ukraine. Above and foremost, Ukraine is to be provided guarantors in the event it is attacked by a non-state actor/s. It will be entitled to a no-fly zone from these countries when warranted within it's borders. These were to be Poland, Canada, Germany and included Turkey in the list (LOL- All NATO members - get it?)
Russia, at the time, countered the matter about Donest/Crimea will rest on a 15-year ceasefire non-conflict zone, and at that 15-year mark can discussion about its future can begin. It will not pursue 'denazification/disarmament'.
As the video shows above, initial talks began and everyone were fairly optimistic. Then BOJO was bored enough and agreed to become the US's lap dog. The rest is history.